mirror of https://github.com/XEphem/XEphem.git
9397 lines
401 KiB
HTML
9397 lines
401 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<html>
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<meta content="text/html; charset=ISO-8859-1"
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<meta
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content="HTML Tidy for Linux/x86 (vers 1st June 2003), see www.w3.org"
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name="generator">
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<title>XEphem Reference Manual</title>
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body { margin-left: 8%; margin-right: 8%; }
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h1 { margin-left: -6%;}
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<body style="color: rgb(0, 0, 0); background-color: rgb(247, 251, 247);"
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alink="#000099" link="#000099" vlink="#990099">
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<div class="title">
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<img style="width: 261px; height: 56px;" alt="" title="" src="png/logo.png">
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<h1>XEphem</h1>
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<p><b>pronounced <i>eks i fem´</i></b></p>
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<h1>Reference Manual</h1>
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<p><b>© 1990-2015 Elwood Charles Downey</b></p>
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<img src="png/valid-html401.png" alt="" height="31" width="88">
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</div>
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<div style="text-align: left;"> <br>
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<ol class="readonly" id="mozToc">
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<!--mozToc h1 1 h2 2 h3 3 h4 4--><li><a href="#mozTocId374556">Introduction</a>
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<ol>
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<li><a href="#mozTocId605914">Quantitative
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information</a></li>
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<li><a href="#mozTocId391132">Local circumstances</a></li>
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<li><a href="#mozTocId403597">Launching XEphem</a>
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<ol>
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<li><a href="#mozTocId644691">Shared and Private Directories</a></li>
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<li><a href="#mozTocId554195">Main window control</a></li>
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</ol>
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</li>
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<li><a href="#mozTocId40933"> Time
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and angle formats</a></li>
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</ol>
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</li>
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<li><a href="#mozTocId376786">Main
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Window</a>
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<ol>
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<li><a href="#mozTocId274172">Main's Help menu
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</a></li>
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<li><a href="#mozTocId634279">Menu bar</a>
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<ol>
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<li><a href="#mozTocId402094">File</a></li>
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<li><a href="#mozTocId36873">View</a></li>
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<li><a href="#mozTocId63622"> Tools</a></li>
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<li><a href="#mozTocId329548">Data</a></li>
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<li><a href="#mozTocId292331">Preferences</a></li>
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</ol>
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</li>
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<li><a href="#mozTocId900244">Sections</a>
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<ol>
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<li><a href="#mozTocId501534"> Local</a>
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<ol>
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<li><a href="#mozTocId872205"> Site Selection</a></li>
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</ol>
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</li>
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<li><a href="#mozTocId635932"> Time</a></li>
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<li><a href="#mozTocId560135"> Calendar</a></li>
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<li><a href="#mozTocId624527">Night</a></li>
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<li><a href="#mozTocId154433"> Looping</a></li>
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</ol>
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</li>
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</ol>
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</li>
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<li><a href="#mozTocId705230">File menu</a>
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<ol>
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<li><a href="#mozTocId795475">System log</a></li>
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<li><a href="#mozTocId557162">Gallery</a>
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<ol>
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<li><a href="#mozTocId895040">File format</a></li>
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</ol>
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</li>
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<li><a href="#mozTocId323368">Network
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Setup</a></li>
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<li><a href="#mozTocId203018"> External Input</a></li>
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</ol>
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</li>
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<li><a href="#mozTocId792957">View menu</a>
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<ol>
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<li><a href="#mozTocId764058">Data Table</a>
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<ol>
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<li><a href="#mozTocId121454">Data setup</a></li>
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</ol>
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</li>
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<li><a href="#mozTocId576774">Sun</a>
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<ol>
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<li><a href="#mozTocId591361">Sun mouse</a></li>
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<li><a href="#mozTocId950828">Sun Control menu
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</a></li>
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<li><a href="#mozTocId141077">Sun Files menu
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</a></li>
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<li><a href="#mozTocId156397">Sun Type menu
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</a></li>
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<li><a href="#mozTocId660536">Sun Size menu</a></li>
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</ol>
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</li>
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<li><a href="#mozTocId427392">Moon</a>
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<ol>
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<li><a href="#mozTocId423766">Moon mouse</a></li>
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<li><a href="#mozTocId691644">Moon Control menu</a></li>
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<li><a href="#mozTocId946969">Moon View menu</a>
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<ol>
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<li><a href="#mozTocId868643">More info...</a></li>
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</ol>
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</li>
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<li><a href="#mozTocId218379">Scale menu</a></li>
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<li><a href="#mozTocId832160">Lunar
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Orbiter IV</a></li>
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</ol>
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</li>
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<li><a href="#mozTocId91149">Earth</a>
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<ol>
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<li><a href="#mozTocId320902">Earth mouse</a></li>
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<li><a href="#mozTocId235796">Earth Control menu</a></li>
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<li><a href="#mozTocId316841">Earth View menu</a>
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<ol>
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<li><a href="#mozTocId19624">Objects dialog</a></li>
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</ol>
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</li>
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</ol>
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</li>
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<li><a href="#mozTocId624734">Mars</a>
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<ol>
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<li><a href="#mozTocId400787">Mars mouse</a></li>
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<li><a href="#mozTocId312560">Mars Control menu</a></li>
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<li><a href="#mozTocId578544">Mars View menu</a>
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<ol>
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<li><a href="#mozTocId328938">Features...</a></li>
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<li><a href="#mozTocId984271">More info...</a></li>
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<li><a href="#mozTocId256891">Moon view...</a></li>
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</ol>
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</li>
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</ol>
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</li>
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<li><a href="#mozTocId369626">Jupiter</a>
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<ol>
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<li><a href="#mozTocId231060">Jupiter mouse</a></li>
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<li><a href="#mozTocId192624">Jupiter Control menu</a></li>
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<li><a href="#mozTocId348716">Jupiter View menu</a>
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<ol>
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<li><a href="#mozTocId944636">More info...</a></li>
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</ol>
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</li>
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</ol>
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</li>
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<li><a href="#mozTocId962916">Saturn</a>
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<ol>
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<li><a href="#mozTocId493832">Saturn mouse</a></li>
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<li><a href="#mozTocId379478">Saturn Control menu</a></li>
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<li><a href="#mozTocId87642">Saturn View menu</a>
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<ol>
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<li><a href="#mozTocId949756">More info...</a></li>
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</ol>
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</li>
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</ol>
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</li>
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<li><a href="#mozTocId621414">Uranus</a>
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<ol>
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<li><a href="#mozTocId644069">Uranus mouse</a></li>
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<li><a href="#mozTocId665534">Uranus Control menu</a></li>
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<li><a href="#mozTocId109743">Uranus View menu</a>
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<ol>
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<li><a href="#mozTocId186995">More info...</a></li>
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</ol>
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</li>
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</ol>
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</li>
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<li><a href="#mozTocId640289">Solar System</a>
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<ol>
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<li><a href="#mozTocId474567">Solar System Scales</a></li>
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<li><a href="#mozTocId533766">Solar System mouse</a></li>
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<li><a href="#mozTocId864834">Solar System Control
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menu</a></li>
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<li><a href="#mozTocId885716">Solar System View
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menu</a></li>
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</ol>
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</li>
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</ol>
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</li>
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<li><a href="#mozTocId792513">Sky View</a>
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<ol>
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<li><a href="#mozTocId692938">Sky View mouse</a></li>
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<li><a href="#mozTocId542032">Toolbars</a></li>
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<li><a href="#mozTocId217563">Scale controls</a></li>
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<li><a href="#mozTocId444921">Trails</a></li>
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<li><a href="#mozTocId564189">Sky View Control
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menu</a>
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<ol>
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<li><a href="#mozTocId515599">Options</a>
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<ol>
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<li><a href="#mozTocId267321">Display mode:</a></li>
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<li><a href="#mozTocId289736">Grid Control:</a></li>
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<li><a href="#mozTocId623583">View Options:</a></li>
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<li><a href="#mozTocId708731">Constellation:
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</a></li>
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<li><a href="#mozTocId353932">Labeling:</a></li>
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</ol>
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</li>
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<li><a href="#mozTocId326208">Filter</a></li>
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<li><a href="#mozTocId35744">Print</a></li>
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<li><a href="#mozTocId864598">List</a></li>
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<li><a href="#mozTocId669677">Horizon</a></li>
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<li><a href="#mozTocId949206">Field Stars</a></li>
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<li><a href="#mozTocId411561"> Favorites</a></li>
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<li><a href="#mozTocId82697">Eyepieces</a></li>
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<li><a href="#mozTocId931036">Coordinates</a></li>
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<li><a href="#mozTocId287757"> User
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annotation</a></li>
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</ol>
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</li>
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<li><a href="#mozTocId505331">Sky View Images menu</a>
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<ol>
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<li><a href="#mozTocId164101">Load and Save FITS
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images
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</a></li>
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<li><a href="#mozTocId883609">Image Analysis Tools</a>
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<ol>
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<li><a href="#mozTocId410584">Brightness and
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Contrast</a></li>
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<li><a href="#mozTocId203653">Cross section Slice</a></li>
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<li><a href="#mozTocId408614">Magnifying Glass</a></li>
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<li><a href="#mozTocId487105">Region of Interest</a></li>
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<li><a href="#mozTocId800569">2D Gaussian
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Measurements</a></li>
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</ol>
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</li>
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<li><a href="#mozTocId941910">Registration
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</a></li>
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<li><a href="#mozTocId771440">WCS Solver</a></li>
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</ol>
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</li>
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<li><a href="#mozTocId618558"> Sky View Favorites
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menu</a></li>
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<li><a href="#mozTocId365647">Sky View Telescope
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menu</a>
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<ol>
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<li><a href="#mozTocId87479">INDI Test Drivers</a></li>
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<li><a href="#mozTocId620571">INDI Configuration
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window</a></li>
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<li><a href="#mozTocId249275">INDI Control Panel</a></li>
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<li><a href="#mozTocId572031">FIFO Control</a></li>
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</ol>
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</li>
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<li><a href="#mozTocId572030">Sky View History menu</a></li>
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<li><a href="#mozTocId535793">Sky View Binary Star Map</a></li>
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</ol>
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</li>
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<li><a href="#mozTocId255075">Tools menu</a>
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<ol>
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<li><a href="#mozTocId138961">Plot values</a></li>
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<li><a href="#mozTocId310002">List values</a></li>
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<li><a href="#mozTocId511473">Solve equation</a></li>
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<li><a href="#mozTocId544617">Find close pairs</a>
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<ol>
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<li><a href="#mozTocId537600">Close Pairs Control
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menu</a></li>
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<li><a href="#mozTocId379485">Close Pairs Options
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menu</a></li>
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<li><a href="#mozTocId201821">Close Pairs Algorithm</a></li>
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</ol>
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</li>
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<li><a href="#mozTocId879084">Night at a Glance</a></li>
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<li><a href="#mozTocId646511">Coordinate converter</a></li>
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<li><a href="#mozTocId535879">Observers
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logbook</a></li>
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<li><a href="#mozTocId617264">Movie
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loop</a></li>
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</ol>
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</li>
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<li><a href="#mozTocId36368">Data menu</a>
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<ol>
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<li><a href="#mozTocId132979">Files</a>
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<ol>
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<li><a href="#mozTocId356973">Files Control menu</a></li>
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<li><a href="#mozTocId468501">File format</a>
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<ol>
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<li><a href="#mozTocId800642"> General format
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rules
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</a></li>
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<li><a href="#mozTocId215848">Format Details</a></li>
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<li><a href="#mozTocId564354">Magnitude models</a></li>
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</ol>
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</li>
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<li><a href="#mozTocId184653">Notes</a></li>
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<li><a href="#mozTocId74433">Two-line Earth
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satellite element sets</a></li>
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</ol>
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</li>
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<li><a href="#mozTocId396689">Index</a></li>
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<li><a href="#mozTocId156306">Favorites</a></li>
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<li><a href="#mozTocId69192">Download
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</a></li>
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<li><a href="#mozTocId147305">Field Stars</a>
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<ol>
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<li><a href="#mozTocId160208">Hubble GSC</a></li>
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<li><a href="#mozTocId676533">USNO A or SA catalogs</a></li>
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<li><a href="#mozTocId619625">Proper Motion catalogs</a></li>
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<li><a href="#mozTocId802428">Skip likely duplicates</a></li>
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<li><a href="#mozTocId289990">Notes</a></li>
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</ol>
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</li>
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</ol>
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</li>
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<li><a href="#mozTocId915560"> Preferences
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</a>
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<ol>
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<li><a href="#mozTocId361550">Fonts</a>
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<ol>
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<li><a href="#mozTocId523543">XLFD</a></li>
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</ol>
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</li>
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<li><a href="#mozTocId759084">Colors</a>
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<ol>
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<li><a href="#mozTocId896872">Colors Control menu</a></li>
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<li><a href="#mozTocId803196">Star colors</a></li>
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</ol>
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</li>
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<li><a href="#mozTocId376242">Save</a></li>
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</ol>
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</li>
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<li><a href="#mozTocId539636">Multifunction Tools</a>
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<ol>
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<li><a href="#mozTocId242681">Trails</a></li>
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<li><a href="#mozTocId231234">Printing</a></li>
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<li><a href="#mozTocId406792">Annotation</a></li>
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</ol>
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</li>
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<li><a href="#mozTocId429783">Credits</a></li>
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<li><a href="#mozTocId402656">Notes</a>
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<ol>
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<li><a href="#mozTocId610542">Horizon</a></li>
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<li><a href="#mozTocId730559">glob Patterns</a></li>
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<li><a href="#mozTocId730558">Accuracy</a></li>
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<li><a href="#mozTocId118721">TODO</a></li>
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<li><a href="#mozTocId982160"> Known Bugs</a></li>
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<li><a href="#mozTocId866585">History</a></li>
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</ol>
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</li>
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</ol>
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</div>
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</div>
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<h1><a class="mozTocH1" name="mozTocId374556"></a> 1 <a name="Intro"></a>Introduction</h1>
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<p>XEphem is a scientific-grade interactive astronomical ephemeris
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package. XEphem:</p>
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<ul>
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<li>computes <span style="font-weight: bold;">heliocentric,
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geocentric and topocentric</span> information for all objects;</li>
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<li>has built-in support for all <span style="font-weight: bold;">planets;
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the moons</span> of Mars, Jupiter, Saturn, Uranus and Earth; central
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meridian longitude of Mars and Jupiter; Saturn's <span
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style="font-weight: bold;">rings;</span> and Jupiter's <span
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style="font-weight: bold;"> Great Red Spot</span>;</li>
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<li>allows <span style="font-weight: bold;">user-defined objects</span>
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including stars, deepsky objects, asteroids, comets and Earth
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satellites.</li>
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<li>provides special efficient handling of <span
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style="font-weight: bold;">large catalogs</span> including Tycho,
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Hipparcos, GSC.<br>
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</li>
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<li>displays data in <span style="font-weight: bold;">configurable
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tabular formats</span> in conjunction with several interactive
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graphical views;</li>
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<li>displays a <span style="font-weight: bold;">night-at-a-glance</span>
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24 hour graphic showing when any selected objects are up;</li>
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<li>displays <span style="font-weight: bold;">3-D stereo Solar
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System views</span> that are particularly well suited for visualizing
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comet trajectories;</li>
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<li>quickly <span style="font-weight: bold;">finds all close pairs</span>
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of objects in the sky;</li>
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<li>sorts and prints all catalogs with very flexible criteria for
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creating custom <span style="font-weight: bold;">observing lists</span>;</li>
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<li>creates <span style="font-weight: bold;">plots of any pairs</span>
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of all data fields throughout the program;</li>
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<li>downloads <span style="font-weight: bold;">current asteroid and
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comets</span> ephemerides from Lowell Observatory and Minor Planet
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Center;</li>
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<li>downloads timely <span style="font-weight: bold;">Earth satellite</span>
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orbital TLE parameters;</li>
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<li>plots true <b>binary system</b> orbits;<br>
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</li>
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<li>downloads <span style="font-weight: bold;">Digitized Sky Survey</span>
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FITS files from STScI or ESO;</li>
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<li>provides a handy <span style="font-weight: bold;">coordinates</span>
|
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<span style="font-weight: bold;">spreadsheet</span> for converting
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among
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equatorial, ecliptic, horizon and galactic frames ;</li>
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<li>displays live SOHO images of the <span style="font-weight: bold;">Sun</span>;<br>
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</li>
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<li>includes a compiler for entering and <span
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style="font-weight: bold;">solving user-written functions</span> using
|
|
any data fields;</li>
|
|
<li>serves as the control point for <span style="font-weight: bold;">GOTO
|
|
telescopes</span> such as Meade LX200 or other external applications;</li>
|
|
<li>displays FITS files <span style="font-weight: bold;">images
|
|
overlaid</span> with database symbols and other graphical information;</li>
|
|
<li>performs automatic star pattern matching to <span
|
|
style="font-weight: bold;">automatically solve for World Coordinate
|
|
System</span> on any image;</li>
|
|
<li>performs 1-click 2D Gaussian relative and absolute <span
|
|
style="font-weight: bold;">photometry;</span></li>
|
|
<li>defines and saves any number of <span style="font-weight: bold;">Eyepieces</span>
|
|
to use in sky maps;</li>
|
|
<li>captures, displays and clips to any number of <span
|
|
style="font-weight: bold;">local horizon profiles</span>;</li>
|
|
<li>stores sets of all Sky View options in <span
|
|
style="font-weight: bold;">history</span> sets for easy playback later;</li>
|
|
<li>prints using high quality <span style="font-weight: bold;">Postscript</span>;</li>
|
|
<li>allows you to assign any number of objects as <span
|
|
style="font-weight: bold;">Favorites</span> for special fast access
|
|
throughout the program, and makes them available even when their
|
|
original databases are no longer loaded;</li>
|
|
<li>provides an extensible <span style="font-weight: bold;">image
|
|
gallery</span> initialized with over 300 beautiful and informative
|
|
color images of deep sky objects;</li>
|
|
<li>provides an <span style="font-weight: bold;">observing logbook</span>
|
|
which is automatically filled in with observing circumstances, with
|
|
searching on most fields;</li>
|
|
<li>displays <span style="font-weight: bold;">magnetic deviation</span>
|
|
for any location.</li>
|
|
<li>create <b>movie loops</b> of any View, NAAG or Plot window.<br>
|
|
</li>
|
|
</ul>
|
|
XEphem can compute information on demand or time can be set to
|
|
increment automatically. In this way a series of computations and
|
|
movies can be generated.<br>
|
|
<h2><a class="mozTocH3" name="mozTocId605914"></a> 1.1 Quantitative
|
|
information</h2>
|
|
<p>Quantitative information available about each object includes:</p>
|
|
<ul>
|
|
<li>RA and Dec,</li>
|
|
<li>local azimuth and altitude,</li>
|
|
<li>distance from sun and earth,</li>
|
|
<li>light travel times,</li>
|
|
<li>heliocentric coordinates,</li>
|
|
<li>galactic coordinates,</li>
|
|
<li>ecliptic coordinates,</li>
|
|
<li>solar elongation,</li>
|
|
<li>angular size,</li>
|
|
<li>visual magnitude,</li>
|
|
<li>illumination percentage,</li>
|
|
<li>local rise and set times and azimuths,</li>
|
|
<li>local transit times and altitude,</li>
|
|
<li>length of time up,</li>
|
|
<li>constellation,</li>
|
|
<li>angular separations between all Favorites.<br>
|
|
</li>
|
|
</ul>
|
|
<h2><a class="mozTocH3" name="mozTocId391132"></a> 1.2 Local circumstances</h2>
|
|
<p>Local observing circumstance information includes</p>
|
|
<ul>
|
|
<li>UTC and local date and time,</li>
|
|
<li>local sidereal time,</li>
|
|
<li>times astronomical, nautical and civil twilight and length of
|
|
night,</li>
|
|
<li>local temperature and pressure (for refraction),</li>
|
|
<li>elevation above sea level (for parallax),</li>
|
|
<li>a monthly calendar.</li>
|
|
</ul>
|
|
Equatorial coordinates may be computed in any four combinations of
|
|
topocentric or geocentric, and apparent or astrometric. When the
|
|
Equinox is set to a fixed date the values are astrometric, that is,
|
|
corrected only for precession and light travel time. When the Equinox
|
|
is set for EOD (Equinox of Date) the values are apparent and are also
|
|
corrected for nutation, aberration and relativistic deflection.
|
|
Topocentric values are further corrected for parallax, augmentation
|
|
and refraction.<br>
|
|
<h2><a class="mozTocH2" name="mozTocId403597"></a> 1.3 <a name="Operation"></a><a
|
|
class="mozTocH1" name="mozTocId313730"></a> Launching XEphem</h2>
|
|
In addition to all the standard X Window System command line arguments,
|
|
XEphem also supports the following command line arguments:<br>
|
|
<br>
|
|
<table
|
|
style="text-align: left; width: 75%; margin-left: auto; margin-right: auto;"
|
|
summary="command line arguments" align="center" cellpadding="2"
|
|
cellspacing="2">
|
|
<tbody>
|
|
<tr>
|
|
<th style="vertical-align: top;">Argument<br>
|
|
</th>
|
|
<th style="vertical-align: top;">Meaning<br>
|
|
</th>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top;">-env <span
|
|
style="font-style: italic;">name</span>=<span
|
|
style="font-style: italic;">value</span><br>
|
|
</td>
|
|
<td style="vertical-align: top;">set internal value for
|
|
environment variable; any number allowed<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top;">-help<br>
|
|
</td>
|
|
<td style="vertical-align: top;">print this then exit<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top;">-install {yes no guess}<br>
|
|
</td>
|
|
<td style="vertical-align: top;">whether to install a private
|
|
colormap, default is guess<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top;">-log<br>
|
|
</td>
|
|
<td style="vertical-align: top;">save exit trouble to private log<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top;">-nosplash<br>
|
|
</td>
|
|
<td style="vertical-align: top;">disable splash screen from now on<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top;">-nowin<br>
|
|
</td>
|
|
<td style="vertical-align: top;">do not restore windows<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top;">-prfb<br>
|
|
</td>
|
|
<td style="vertical-align: top;">print all internal default
|
|
resources then exit<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top;">-resfile <span
|
|
style="font-style: italic;">f</span><br>
|
|
</td>
|
|
<td style="vertical-align: top;">load alternate X resource file<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top;">-splash<br>
|
|
</td>
|
|
<td style="vertical-align: top;">show splash screen from now on<br>
|
|
</td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
<br>
|
|
<br>
|
|
<h3><a class="mozTocH3" name="mozTocId644691"></a> 1.3.1 <a
|
|
name="SharedPrivateDirs"></a>Shared and Private Directories</h3>
|
|
When XEphem is launched it looks for a file named <span
|
|
style="font-family: monospace;">.xephemrc</span> in the user's <span
|
|
style="font-family: monospace;">$HOME</span> directory. This file is
|
|
optional. If it exists, it should contain a line with the following
|
|
form:<br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> <span style="font-family: monospace;">XEphem.PrivateDir:
|
|
~/.xephem</span> </div>
|
|
<br>
|
|
The directory named on the right is where XEphem will create and look
|
|
for <span style="font-style: italic;">Private</span> files, so-called
|
|
because on a multiuser system they are expected to be separated on a
|
|
per-user basis. A leading "~" in the file name can be used to refer to <span
|
|
style="font-family: monospace;">$HOME</span>, your login directory.
|
|
A leading "." in the file name can be used to refer to the current
|
|
working directory of the running program. The example above causes the
|
|
Private directory to be <span style="font-family: monospace;">.xephem</span>
|
|
in the users <span style="font-family: monospace;">$HOME</span>
|
|
directory. If <span style="font-family: monospace;">.xephemrc</span>
|
|
does not exist or does not contain this line the default Private
|
|
directory is <span style="font-family: monospace;">~/.xephem</span>.
|
|
The private directory will be created if it does not already exist.<br>
|
|
<br>
|
|
XEphem then also searches for another directory for <i>Shared</i>
|
|
files. This directory contains files presumed to be shared
|
|
among all XEphem users on a system. Files in this directory are never
|
|
modified by XEphem. They include databases of objects, supporting
|
|
images and other files. This directory is specified in a resource file
|
|
named <span style="font-family: monospace;">XEphem</span> which may be
|
|
located in any of the standard X Window System directories, in
|
|
/etc or within the Private directory (see above). It should contain a
|
|
line with the following form:<br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> <span style="font-family: monospace;">XEphem.ShareDir:
|
|
/usr/local/xephem</span> </div>
|
|
<br>
|
|
Next, XEphem sets the initial values of most options and settings from
|
|
other entries in the resource file. Settings which do not appear will
|
|
use their internal default values. Internal defaults may be printed
|
|
using the -prfb command line option.<br>
|
|
<h3><a class="mozTocH3" name="mozTocId554195"></a> 1.3.2 Main window control</h3>
|
|
XEphem starts by showing the Main window with each parameter set to
|
|
its default value. The parameters on the Main window are primarily
|
|
devoted to describing the location and time for which all other data
|
|
in XEphem are computed.<br>
|
|
<br>
|
|
Most fields on the Main window may be changed by clicking them. A
|
|
prompt window with a brief explanation of the field will appear. A new
|
|
value may be typed into the text field provided. If <span
|
|
style="font-weight: bold;">Ok</span> is clicked the new value will be
|
|
used; if <span style="font-weight: bold;">Cancel</span> is clicked the
|
|
field will be left unchanged. In either case, the prompt window goes
|
|
away. Some of the windows have an extra button which offers a handy
|
|
way to enter frequently used values for the field.<br>
|
|
<br>
|
|
If you change a field on the Main window that would invalidate any of
|
|
the other fields in any XEphem window the message NEW CIRCUMSTANCES
|
|
flashes near the top of the Main window. This will continue until the
|
|
next Update occurs. If you change any field that causes new
|
|
circumstances, the Step value is not added to the current time before
|
|
the next loop.<br>
|
|
<br>
|
|
You can change time manually like any other fields or you can set up
|
|
looping to advance time automatically with specified pauses between
|
|
each step. The prominent button at the bottom of the Main window
|
|
labeled <span style="font-weight: bold;">Update</span> causes all
|
|
other
|
|
windows throughout XEphem will be recomputed with the new time.
|
|
Looping effectively presses this button for you. See <a
|
|
href="#main_looping">Looping</a>.<br>
|
|
<br>
|
|
Some graphical views have a push button marked <span
|
|
style="font-weight: bold;">Movie Demo</span>. This is a convenient way
|
|
to start and stop a sample movie sequence. If XEphem is currently idle
|
|
then pushing the button will set the Main window Step size to a value
|
|
that will yield a pleasing motion effect and start looping with a very
|
|
large number of steps. If XEphem is already looping then pushing the
|
|
button will cause it to stop and set Main window N Steps to 1. The
|
|
Main window Stop control can also stop the looping in the usual way.
|
|
<h2><a class="mozTocH1" name="mozTocId40933"></a> 1.4 <a name="Date_time"></a>Time
|
|
and angle formats</h2>
|
|
Time and RA are displayed as h:m:s. They may be entered the same way
|
|
or the color (:) may be entered as slash (/) semicolor (;) comma (,)
|
|
or space. Other angular quantities, such as declination, azimuth,
|
|
altitude, longitude and latitude, are entered and displayed as d:m:s
|
|
but
|
|
otherwise use the same rules.<br>
|
|
<br>
|
|
Components of a sexagesimal field may be entered as floating point
|
|
numbers. For example 10:20:30 may also be entered as either 10:20.5 or
|
|
10.34167.<br>
|
|
<br>
|
|
Negative values are indicated by one hyphen (-) before the first
|
|
character.<br>
|
|
<br>
|
|
Dates are entered and displayed in any one of the forms month/day/year,
|
|
year/month/day or day/month/year, depending on the <a
|
|
href="#MainMenu_preferences">Preferences</a> selection on the Main
|
|
menubar. The slash (/) may also be entered as hyphen (-) semicolon (;)
|
|
or comma (,). Note you must always enter the full year.<br>
|
|
<br>
|
|
When the day portion of a date is an integer, the time does not change.
|
|
When the day portion of a date is entered as a floating point number,
|
|
the time will also change to correspond to the fractional portion of
|
|
the day. For example, using the preference m/d/y, entering a date of
|
|
1/1.5/1995 will set the date to 1/1/1995 and the time to 12:00:00. To
|
|
get this effect with a whole day, include the decimal point. For
|
|
example, 1/1.0/2002 will set the date to 1/1/2002 and the time to
|
|
0:00:00.<br>
|
|
<br>
|
|
You may also enter a date as a decimal year, as in 1990.12345.<br>
|
|
<br>
|
|
Negative years indicate BC dates. For example, Jan 1, 1 BC is given
|
|
as 1/1/-1. Before you ask, yes, "1-1--1" works for 1 BC. There is no
|
|
year 0.
|
|
<h1><a class="mozTocH1" name="mozTocId376786"></a> 2.0 <a name="MainMenu"></a>Main
|
|
Window</h1>
|
|
<img style="width: 303px; height: 489px;" alt="" title=""
|
|
src="png/main.png" align="right" hspace="20">XEphem's
|
|
main window is divided into five regions plus the menu bar across the
|
|
top for selecting the principle functions of XEphem. Each window
|
|
opened from the menu bar has its own Help.<br>
|
|
<br>
|
|
Beneath the XEphem logo image is a status line that contains a short
|
|
description of what XEphem is doing at the moment with regards to its
|
|
looping behavior.<br>
|
|
<br>
|
|
Below the status line is room for the NEW CIRCUMSTANCES message. When
|
|
you change any field on the Main window that could invalidate any of
|
|
the other fields or views throughout XEphem this message flashes until
|
|
at least one screen Update occurs to get everything up to date again.<br>
|
|
<br>
|
|
<h2><a class="mozTocH2" name="mozTocId274172"></a> 2.1 <span
|
|
style="font-weight: bold;">Main's Help menu</span><br>
|
|
</h2>
|
|
XEphem help is written in html version 4.01 transitional and requires a
|
|
browser
|
|
to read. The text is all in one file, xephem.html, located in
|
|
auxil/help within the Shared directory path. Anchors throughout the
|
|
file
|
|
allow XEphem to specify exactly where to jump for each Help entry.<br>
|
|
<br>
|
|
<span style="font-family: monospace;">Help </span><span
|
|
style="font-family: monospace;">» </span><span
|
|
style="font-family: monospace;">Configure<br>
|
|
<br>
|
|
</span>
|
|
<div style="margin-left: 40px;">This Help entry is used to set how
|
|
XEphem sends a URL to your
|
|
browser. It must be correct before any other Help can be used. It
|
|
displays a table showing sample
|
|
shell commands that accomplish this for several popular browsers
|
|
including mozilla, netscape, opera, konqueror and safari. Each time %s
|
|
appears in the definition the full path to the xephem.html will be
|
|
substituted. If you figure
|
|
out how to configure for another browser or you know of a better
|
|
definition please send us your results and we will post on our web site.<br>
|
|
<br>
|
|
Note the entry for using IE under <a href="http://www.cygwin.com"
|
|
target="new">cygwin</a>. In order for this to work,
|
|
you must create an
|
|
environment variable before running XEphem named XEHELPURL set to the
|
|
full Windows path of the xephem.html file using Windows filespec
|
|
notation. The value of this variable is substituted for each %s
|
|
appearing in the definition for IE.<br>
|
|
</div>
|
|
<br>
|
|
<span style="font-family: monospace;">Help » on Context</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;">This Help entry turns the cursor into a
|
|
Question Mark. Roaming the cursor over any
|
|
control in XEphem will show its bubble help tip whether or not the tips
|
|
<a href="#MainMenu_preferences">Preference</a> is active. Press the
|
|
left
|
|
mouse button to end this behavior and resume normal operation.<br>
|
|
</div>
|
|
<br>
|
|
All remaining Help entries just bring up additional information as one
|
|
would expect. If you are new to XEphem, we suggest you begin by reading
|
|
the next three entries in order, Introduction, Operation and Triad
|
|
formats, then feel free to explore.<br>
|
|
<br>
|
|
<h2><a class="mozTocH2" name="mozTocId634279"></a> 2.2 Menu bar</h2>
|
|
<h3><a class="mozTocH3" name="mozTocId402094"></a> 2.2.1 <a
|
|
name="MainMenu_file"></a> <a class="mozTocH3" name="mozTocId785477"></a>File</h3>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">System log...</span> displays a
|
|
scrolled list of informational messages and alert. XEphem may beep
|
|
whenever a new message is added, depending on the Log Bell <a
|
|
href="#MainMenu_preferences">preference.</a> See <a href="#SysLog">System
|
|
log</a>.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Gallery...</span> displays a
|
|
list of installed color images and allows browsing or marking in Sky
|
|
View. See <a href="#Gallery">Gallery</a>.<br>
|
|
</li>
|
|
</ul>
|
|
<ul>
|
|
<li style="font-weight: bold;">Network setup... <span
|
|
style="font-weight: normal;">displays a window offering choices for
|
|
how XEphem accesses</span> <span style="font-weight: normal;">the
|
|
Internet. See <a href="#WebDB">Internet.</a><br>
|
|
</span></li>
|
|
</ul>
|
|
<ul>
|
|
<li style="font-weight: bold;">External file... <span
|
|
style="font-weight: normal;">drives XEphem from a file containing
|
|
times and latitude/longitude</span> <span style="font-weight: normal;">locations.
|
|
See <a href="#ExternalInput">External input</a>.<br>
|
|
</span></li>
|
|
</ul>
|
|
<ul>
|
|
<li style="font-weight: bold;">Progress Meter... <span
|
|
style="font-weight: normal;">displays a simple bar graph of XEphem
|
|
progress. The accuracy and</span> <span style="font-weight: normal;">usefulness
|
|
of the display are somewhat problematic at</span> <span
|
|
style="font-weight: normal;">this time.</span><br>
|
|
</li>
|
|
</ul>
|
|
<ul>
|
|
<li style="font-weight: bold;">Forward 1 Step <span
|
|
style="font-weight: normal;">causes Time to be changed by one Step
|
|
value. This action can also be performed when the cursor is over any
|
|
XEphem window by typing Control-f. Invoking this command also stops
|
|
looping if it is running.</span></li>
|
|
</ul>
|
|
<ul>
|
|
<li style="font-weight: bold;">Backward 1 Step <span
|
|
style="font-weight: normal;">causes Time to be changed by the negative
|
|
of one Step value. This action can also be performed when the cursor
|
|
is over any XEphem window by typing Control-b. Invoking this command
|
|
also stops looping if it is running.</span></li>
|
|
</ul>
|
|
<ul>
|
|
<li style="font-weight: bold;">Update <span
|
|
style="font-weight: normal;">performs the same action as the Update
|
|
button across the bottom of the Main window. This can also be performed
|
|
by typing Control-u in any XEphem window.</span> See <a
|
|
style="font-weight: normal;" href="#main_looping">Looping</a><span
|
|
style="font-weight: normal;">.</span><br>
|
|
</li>
|
|
</ul>
|
|
<ul>
|
|
<li><b>Quit...</b> exits XEphem. If any resources have been modified
|
|
and <span style="font-family: monospace;">Preferences »
|
|
Confirmations</span> is On, a reminder will first appear and allow
|
|
you to bring up the Save window if desired. This can also be
|
|
performed by typing Control-d in any XEphem window.</li>
|
|
</ul>
|
|
<h3><a class="mozTocH2" name="mozTocId36873"></a> 2.2.2 <a name="MainMenu_view"></a>View</h3>
|
|
The View menu gives access to all of the several XEphem
|
|
specialized displays.<br>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Data Table...</span> highly
|
|
configurable, show any from a selection of over 30 parameters for
|
|
each Favorite object. See <a href="#Favorites">Favorites</a> and <a
|
|
href="#Data_Table">Data table</a>.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Sun...</span> show SOHO images
|
|
of
|
|
the Sun, measure current RA and Dec of solar features. See <a
|
|
href="#Sun">Sun</a>.<br>
|
|
</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Moon...</span> show real lunar
|
|
image, mark hundreds of natural and artificial features, compute sun
|
|
and
|
|
observing circumstances. See <a href="#Moon">Moon.</a><br>
|
|
</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Earth...</span> show spherical
|
|
or
|
|
cylindrical projection, satellite ground tracks. See <a href="#Earth">Earth.</a><br>
|
|
</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Jupiter...</span> show planet
|
|
image with moons and shadows. See <a href="#Jupiter">Jupiter.</a><br>
|
|
</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Saturn...</span> show planet
|
|
image with moons and shadows. See <a href="#Saturn">Saturn</a>.<br>
|
|
</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Uranus...</span> show planet
|
|
symbol with moons. See <a href="#Uranus">Uranus</a>.<br>
|
|
</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Sky View...</span> the showpiece
|
|
of XEphem, display maps, images, trails. See <a href="#SkyView">Sky
|
|
View</a>.<br>
|
|
</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Solar System...</span> 3D and
|
|
perspective diagrams include asteroids, comet trajectories. See <a
|
|
href="#Solsys">Solar System</a>.<br>
|
|
</li>
|
|
</ul>
|
|
<h3><a class="mozTocH2" name="mozTocId63622"></a> 2.2.3 <a
|
|
name="MainMenu_tools"></a>Tools</h3>
|
|
The Tools menu gives access to windows allowing full control
|
|
of the following functions:<br>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Plot values...</span> plot pairs
|
|
of any data values shown throughout XEphem. See <a href="#Plot">Plotting</a>.<br>
|
|
</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">List values...</span> print
|
|
columnar lists of any data values shown throughout XEphem. See <a
|
|
href="#Listing">Listing</a><br>
|
|
</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Solve equation...</span> define
|
|
and solve any mathematical function using any data values shown
|
|
throughout XEphem. See <a href="#Search">Solver</a>.<br>
|
|
</li>
|
|
</ul>
|
|
<ul>
|
|
<li style="font-weight: bold;">Find close pairs... <span
|
|
style="font-weight: normal;">search all loaded database objects and
|
|
sort all pairs by increasing separation. See <a href="#CloseObjects">Close
|
|
pairs</a>.<br>
|
|
</span></li>
|
|
</ul>
|
|
<ul>
|
|
<li style="font-weight: bold;">Night at a glance... <span
|
|
style="font-weight: normal;">display when all Favorite objects are
|
|
up over a 24 hour period. See <a href="#NightAtAGlance">Night at a
|
|
Glance</a>.<br>
|
|
</span></li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Coordinates converter...</span>
|
|
enter one of equatorial, horizon, ecliptic or galactic coordinates
|
|
and show the others. See <a href="#Coord_conv">Coordinate converter</a>.<br>
|
|
</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Observers log book...</span>
|
|
click on a target in Sky View to fill in standard observing fields,
|
|
add your own notes and save, later browse or search for entries. See <a
|
|
href="#ObsLog">Observers logbook</a>.<br>
|
|
</li>
|
|
</ul>
|
|
<h3><a class="mozTocH2" name="mozTocId329548"></a> 2.2.4 <a
|
|
name="MainMenu_objects"></a>Data</h3>
|
|
The Data menu gives access to windows which pertain to
|
|
managing the objects in memory.<br>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Files...</span> adds and deletes
|
|
catalogs of objects to and from memory. The window also displays
|
|
overall
|
|
statistics of the number of each type of object in memory. See <a
|
|
href="#Database_files">Data Files</a>.<br>
|
|
</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Index...</span> searches and
|
|
displays all information about any given object in memory. Also can
|
|
be used to center the Sky View over any object. See <a href="#Object">Data
|
|
Index</a>.<br>
|
|
</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Favorites...</span> adds,
|
|
enables, sorts and deletes the set of objects you wish to have easy
|
|
access to. See <a href="#Favorites">Favorites.</a><br>
|
|
</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Internet...</span> provides a
|
|
convenient means to update XEphem databases from the Net. The window
|
|
comes preconfigured to get timely asteroid, comet and Earth
|
|
satellite catalogs. See <a href="#WebDB">Internet</a>.<br>
|
|
</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Field stars...</span> sets up
|
|
how and whether to read several very large databases of faint stars
|
|
which XEphem refers to as "field stars See <a href="#FieldStars">Field
|
|
stars.</a><br clear="all">
|
|
</li>
|
|
</ul>
|
|
<h3><a class="mozTocH2" name="mozTocId292331"></a> 2.2.5 <a
|
|
name="MainMenu_preferences"></a>Preferences</h3>
|
|
The Preferences pulldown lists the available preferences that may be
|
|
changed at run time. Whenever any are changed, all effected fields are
|
|
immediately recalculated and redisplayed throughout XEphem. The simple
|
|
preferences include:<br style="font-weight: bold;">
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Equatorial: Topocentric,
|
|
Geocentric</span>. controls whether the RA and Dec values displayed
|
|
throughout XEphem are for the current local surface location
|
|
(topocentric) or from the center of the Earth. (Alt/Az values are,
|
|
of course, always topocentric.)</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Precision: Hi, Low</span>
|
|
controls how much precision is shown for most angles. This is a change
|
|
in display format only and does not imply a change in accuracy.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Log Bell: On, Off</span> whether
|
|
to ring the bell each time a new message is added to the System log
|
|
window. The System log window is accessible via the File menu in the
|
|
Main menu bar. See <a href="#SysLog">System log</a>.<br>
|
|
</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Prompt Prefill: Yes, No</span>
|
|
whether prompt strings from the Main window and Search windows are
|
|
filled with the current value or blanked out. This is also handy to
|
|
allow copy/paste of these values.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Units: English, Metric</span>
|
|
whether local topocentric circumstances are given in English or
|
|
Metric units of measure.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Time zone: UTC, Local</span>
|
|
whether the time stamp below each major view, the rise/transit/set
|
|
times in the Data Table window and the dawn/dusk times and the
|
|
calendar in the Main window refer to UTC or local time.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Show help tips: Yes, No</span>
|
|
whether additional help is available immediately for all selectable
|
|
buttons and controls using small brief windows near the control.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Confirmations: Yes, No</span>
|
|
whether operations which basically can not be undone or which might
|
|
have irreversible consequences will be preceded with a confirmation
|
|
window. Examples include exiting XEphem or overwriting an existing
|
|
file.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Start week on: Saturday, Sunday,
|
|
Monday</span> sets the day on which weeks begin in the Main calendar.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Date formats: M/D/Y, Y/M/D,
|
|
D/M/Y</span> whether dates are shown and entered in month/day/year,
|
|
year/month/day or day/month/year format.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Fonts...</span> displays a
|
|
window
|
|
to experiment with fonts while you watch. See <a href="#Save_fonts">fonts</a>.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Colors...</span> displays a
|
|
window to experiment with colors while you watch. See <a
|
|
href="#Save_colors">colors</a>.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Save...</span> displays a window
|
|
which shows how the current functional settings differ from their
|
|
defaults and allows them to be saved. See <a href="#Save">save</a>.</li>
|
|
</ul>
|
|
<h2><a class="mozTocH2" name="mozTocId900244"></a> 2.3 Sections</h2>
|
|
The Main window is divided into five basic sections.<br>
|
|
<h3><a class="mozTocH2" name="mozTocId501534"></a> 2.3.1 Local</h3>
|
|
<img style="width: 162px; height: 163px;" alt="" title=""
|
|
src="png/main-local.png" align="right" hspace="20">
|
|
<ul>
|
|
<li><span style="font-weight: bold;">[Site name]</span> Above the
|
|
Latitude field is a button which can display the current site name.
|
|
Pressing this button will bring up a list of cities and
|
|
observatories. See <a href="#MainMenu_sites_dialog">Sites</a>.<br>
|
|
</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Latitude</span> Local geographic
|
|
latitude, positive degrees north of equator. Changing this will
|
|
disable automatic computation of Daylight Savings Time.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Longitude</span> Local
|
|
longitude,
|
|
positive degrees west of Greenwich meridian. Changing this will
|
|
disable automatic computation of Daylight Savings Time. A sensible
|
|
Timezone is created based on one hour for each 15 degrees from 0.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Elevation</span> Local elevation
|
|
of the ground above sea level, in feet or meters. (see
|
|
implementation notes). Used in topocentric parallax correction.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Temp</span> Local surface air
|
|
temperature, in °F or C. Used in refraction correction.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Atm Pres</span> Local surface
|
|
air pressure, in inches of mercury or hPa. Used in refraction
|
|
correction.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Equinox</span> When set to a
|
|
year, this is the desired epoch to which the RA/Dec fields are
|
|
precessed, referred to as the astrometric place. When this is set to
|
|
EOD, all RA/Dec values are precessed to the current XEphem time, and
|
|
corrected for nutation, aberration and deflection, referred to as
|
|
the apparent place.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Mag decl</span> This is the
|
|
amount by which the horizontal component of the Earth's magnetic
|
|
field varies from true north. Put another way,true az = magnetic
|
|
bearing - mag decl. The model is stored in the file wmm.cof in the
|
|
auxil directory of the shared directory. It is valid for 2000
|
|
through the end of 2004. Check <a
|
|
href="http://www.ngdc.noaa.gov/seg/potfld/DoDWMM.shtml" target="new">http://www.ngdc.noaa.gov/seg/potfld/DoDWMM.shtml</a>
|
|
for updates.<br clear="all">
|
|
</li>
|
|
</ul>
|
|
<h4><a class="mozTocH4" name="mozTocId872205"></a> 2.3.1.1 <a
|
|
name="MainMenu_sites_dialog"></a> Site Selection</h4>
|
|
<img style="width: 349px; height: 430px;" alt="" title=""
|
|
src="png/sites.png" align="right" hspace="20"> This
|
|
window allows you to search, load and add to a collection of predefined
|
|
sites.<br>
|
|
<br>
|
|
The scrolled list at the top lists the complete set of currently
|
|
defined sites. Clicking on one will copy it to the <span
|
|
style="font-weight: bold;">Set</span> text field. Double clicking on
|
|
one will also install it to the Main window, as will clicking on Set
|
|
or typing Enter over the select text field.<br>
|
|
<br>
|
|
To search for a particular site, either scroll through the list or
|
|
type a <a href="xephem.html#glob">glob</a> pattern in the <span
|
|
style="font-weight: bold;">Search</span> text field. Clicking on
|
|
Search or typing Enter in the search text field will scroll the list to
|
|
the
|
|
next site that matches the search text.<br>
|
|
<br>
|
|
<span style="font-weight: bold;">Creating new sites.</span><br>
|
|
<br>
|
|
Clicking <span style="font-weight: bold;">Create</span> expands the
|
|
dialog to add fields for creating new sites. Fill in the fields then
|
|
click <span style="font-weight: bold;">Set main</span> to test the
|
|
entry and <span style="font-weight: bold;">Save</span> to add it to
|
|
the
|
|
collection on disk.<br>
|
|
<br style="font-weight: bold;">
|
|
<span style="font-weight: bold;">File format</span>:<br>
|
|
<br>
|
|
XEphem stores sites in the file named <b>xephem_sites</b>. One may
|
|
reside in
|
|
either or both the <a href="#SharedPrivateDirs">Shared and Private</a>
|
|
directories. The Sites window always checks both.<br>
|
|
<br>
|
|
Each line in the file consists of 5 fields, each separated by a
|
|
semicolon (;):<var><span style="font-family: monospace;"><br>
|
|
<br>
|
|
</span></var>
|
|
<div style="margin-left: 40px;"> <var>Name ; Latitude ; Longitude ;
|
|
Elevation ; Timezone<span style="font-family: monospace;"><br>
|
|
<br>
|
|
</span></var> </div>
|
|
where:<br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> <span style="font-style: italic;">Name</span>
|
|
is the City, State, Country or other designation, up to 40
|
|
characters. </div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> <span style="font-style: italic;">Latitude</span>
|
|
is DD MM SS, followed by an N or S to indicate north or south of the
|
|
equator. Each portion is separated by a blank. </div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> <span style="font-style: italic;">Longitude</span>
|
|
is in DDD MM SS, followed by an E or W to indicate east or west of
|
|
the prime meridian in Greenwich, England. Each portion is separated
|
|
by a blank. </div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> <span style="font-style: italic;">Elevation</span>
|
|
is in meters. If you do not know your elevation, put "-1.0". </div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> <span style="font-style: italic;">Timezone</span>
|
|
indicates the offset from GMT and details of savings time formatted
|
|
as follows: </div>
|
|
<br>
|
|
<div style="margin-left: 80px;"> <span style="font-family: monospace;">std
|
|
offset dst [offset],start[/time],end[/time]</span> </div>
|
|
<br>
|
|
<div style="margin-left: 80px;"> There are no spaces in the
|
|
specification. All fields except the initial
|
|
<span style="font-family: monospace;">std</span>
|
|
string are optional. It specifies the name of the standard time zone
|
|
and must
|
|
be three or more alphabetic characters.
|
|
</div>
|
|
<br>
|
|
<div style="margin-left: 80px;"> The
|
|
<span style="font-family: monospace;">offset</span>
|
|
string indicates the value added to the local time to arrive at
|
|
Coordinated
|
|
Universal Time. The offset has the format
|
|
<span style="font-family: monospace;">hh[:mm[:ss]]</span>.
|
|
The minutes (mm) and seconds (ss) are optional. If preceded by a minus
|
|
(-) the timezone shall be east of the Prime Meridian;
|
|
otherwise, it shall be west (which may be indicated by an optional
|
|
preceding
|
|
plus (+)).
|
|
</div>
|
|
<br>
|
|
<div style="margin-left: 80px;"> The <span
|
|
style="font-family: monospace;">dst</span> string and second <span
|
|
style="font-family: monospace;">offset</span> specify the name and
|
|
difference between the daylight savings time zone and the standard
|
|
time zone. If the offset is omitted, it defaults to one hour ahead
|
|
of standard time. </div>
|
|
<br>
|
|
<div style="margin-left: 80px;"> The <span
|
|
style="font-family: monospace;">start</span> field specifies when
|
|
daylight savings time goes into effect and the <span
|
|
style="font-family: monospace;">end</span> field specifies when the
|
|
change is made back to standard time. These fields have the
|
|
format <span style="font-family: monospace;">Mm.w.d</span> which
|
|
specifies day d (0 <= d <= 6) of week w (1 <= w <= 5) in
|
|
month m (1 <= m <= 12). Day 0 is Sunday. Week 1 is the
|
|
first week in which day d occurs and week 5 is the last week in
|
|
which day d occurs. If omitted, Savings time will begin the first
|
|
Sunday in April and end the last Sunday of October. </div>
|
|
<br>
|
|
<div style="margin-left: 80px;"> The <span
|
|
style="font-family: monospace;">time</span> fields specify when, in
|
|
the local time currently in effect, the change to the other time
|
|
occurs. If omitted, the default is 2:00:00. </div>
|
|
<br>
|
|
Here are a few examples:<br>
|
|
<br>
|
|
<span style="font-family: monospace;">Munich, Germany
|
|
; 48 14 0 N ; 11 57 0 E ; 523 ;
|
|
MET-1METDST,M3.5.0,M10.5.0</span><br style="font-family: monospace;">
|
|
<span style="font-family: monospace;">New York, New York ; 40 45 6 N
|
|
; 73 59 39 W ; 16.8 ; EST5EDT</span><br
|
|
style="font-family: monospace;">
|
|
<span style="font-family: monospace;">Sydney, Australia ; 33 52
|
|
0 S ; 151 12 0 E ; 7.6 ; EST-10EST,M10.5.0,M3.5.0</span><br
|
|
style="font-family: monospace;">
|
|
<br>
|
|
Lines in the file which do not conform to this structure are ignored.<br>
|
|
<h3><a class="mozTocH2" name="mozTocId635932"></a> 2.3.2 Time</h3>
|
|
<img style="width: 167px; height: 184px;" alt="" title=""
|
|
src="png/main-time.png" align="right" hspace="20">
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Julian</span> Number of days
|
|
since noon 4713 BC to about 1-second accuracy. Used as a uniform
|
|
time scale.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">UTC Date</span> The UTC date.
|
|
UTC is Universal Coordinated Time, the basis,after adjusting for
|
|
time zones, for the official "civil" time people set their clocks
|
|
to. Every year or so it is adjusted via a leap second so it stays
|
|
within 0.9 seconds of UT1, which varies continuously with the slight
|
|
irregularities of the rotational motion of the Earth.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">UTC Time</span> The UTC time.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Sidereal</span> The apparent
|
|
sidereal time for the current time and location. Equals the apparent
|
|
RA at the local meridian.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">TZ Name</span> The local time
|
|
zone name. The name may be fixed to any short mnemonic. Setting this
|
|
manually turns off automatic computation of Daylight Savings Time.
|
|
When auto DST is on, a small clock is shown at the top right of the
|
|
Time section.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">TZ Offset</span> Hours local
|
|
time is behind UTC, i.e., positive west or negative east of
|
|
Greenwich. Setting this manually turns off automatic computation of
|
|
Daylight Savings Time.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Local Date</span> The local
|
|
date. This is UTC date minus the value of TZ Offset.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Local Time</span> The local
|
|
time. This is UTC time minus the value of TZ Offset.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Delta T</span> TT-UT1. Number
|
|
of seconds by which Terrestrial Time (aka Ephemeris Time prior to
|
|
1982) leads UT1. TT is generally of interest when calculating the
|
|
positions of solar system objects because it is a continuous time
|
|
scale unaffected by the Earth's rotational vagaries. The term
|
|
Terrestrial means it is adjusted for the relativistic effects of
|
|
gravity and the Earth's revolution around the Sun. UT1 or UTC is of
|
|
interest when relating those positions to the horizon to produce
|
|
altitudes and azimuths. The value may be computed automatically
|
|
based on the current time or entered manually (in which case it will
|
|
not change). The algorithm uses values tabulated in the Astronomical
|
|
Almanac for years 1620.0 through 1998.0, and is accurate to within a
|
|
few seconds over that interval. Dates prior are from Stephenson and
|
|
Morrison or K. M. Borkowski, with an estimated error of 15 minutes at
|
|
1500 B.C. A linear extrapolation formula predicts future values.<br
|
|
clear="all">
|
|
</li>
|
|
</ul>
|
|
<h3><a class="mozTocH2" name="mozTocId560135"></a> 2.3.3 Calendar</h3>
|
|
<img style="width: 136px; height: 163px;" alt="" title=""
|
|
src="png/main-calendar.png" align="right" hspace="20">The
|
|
calendar on the right of the Main window is based on local time or
|
|
UTC, depending upon the Time Zone preference. Clicking a date button
|
|
will set the date. Clicking dates before the first of the month and
|
|
after the last of the month will also change month or year as
|
|
necessary. The month and year buttons pop up menus that allow these to
|
|
be changed as well. At the bottom the <span style="font-weight: bold;">Now</span>
|
|
button sets the time and date to the computer clock. The arrow buttons
|
|
move backwards or forwards by one day or week. Except for Now, using
|
|
the
|
|
calendar does not change the current time, just the date.<br>
|
|
<p>New and Full Moons are marked on the day on which they occur in
|
|
the selected time zone.</p>
|
|
<br clear="all">
|
|
<h3><a class="mozTocH3" name="mozTocId624527"></a> 2.3.4 <a
|
|
name="Main_night_section"></a> <a class="mozTocH2" name="mozTocId335903"></a>Night</h3>
|
|
<img style="width: 129px; height: 110px;" alt="" title=""
|
|
src="png/main-night.png" align="right" hspace="20">
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Sun icon</span> When the sun
|
|
is above the local horizon a small sun symbol is drawn in the upper
|
|
left corner of this section.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Moon icon</span> When the moon
|
|
is
|
|
above the local horizon a small symbol is drawn in the upper right
|
|
corner of this section depicting the approximate phase of the moon.
|
|
The brighter of the foreground and background colors is used to draw
|
|
the portion in sun light.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Sun Dip</span> The number of
|
|
degrees the Sun is below the horizon that we wish to call twilight.
|
|
Common definitions include:<br>
|
|
<br>
|
|
<ul>
|
|
<li>Civil = Sun 6 degrees down (can just tell whether headlights
|
|
are on),</li>
|
|
<li>Nautical = Sun is 12 degrees down (sky and ocean merge),</li>
|
|
<li>Astronomical = Sun is 18 degrees down (dark as it gets).</li>
|
|
</ul>
|
|
</li>
|
|
</ul>
|
|
<div style="margin-left: 40px;"> The Sun Dip setting applies to the
|
|
following fields:<br>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Dawn</span> Local or UTC time
|
|
when the Sun center is Sun dip degrees below the horizon before sunrise
|
|
today.</li>
|
|
<li><span style="font-weight: bold;">Dusk</span> Local or UTC time
|
|
when the Sun center is Sun dip degrees below the horizon after sunset
|
|
today.</li>
|
|
<li><span style="font-weight: bold;">Length</span> Length of
|
|
astronomical night, i.e., Dawn - Dusk. If this and the display for
|
|
Dawn and Dusk are shown as "-----", it means the Sun is either
|
|
always below or always above Sun dip degrees below the horizon on
|
|
this particular day.</li>
|
|
</ul>
|
|
<br>
|
|
N.B. These three fields always apply to the local current day.
|
|
Difficulties arise when these events occur within 4 minutes of local
|
|
midnight with respect to the time zone defined by TZ Offset. In
|
|
particular, if these fields are not behaving as you would expect,
|
|
check that the TZ Offset is set commensurate with the current
|
|
Longitude. </div>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">LST@0</span> Local Sidereal
|
|
Time at next local Midnight, as per the time zone.<br clear="all">
|
|
</li>
|
|
</ul>
|
|
<h3><a class="mozTocH2" name="mozTocId154433"></a> 2.3.5 <a
|
|
name="main_looping"></a>Looping</h3>
|
|
<img style="width: 129px; height: 75px;" alt="" title=""
|
|
src="png/main-looping.png" align="right" hspace="20">
|
|
<ul>
|
|
<li><span style="font-weight: bold;">-1</span> <span
|
|
style="font-weight: bold;">+1</span> These are shortcuts to go
|
|
backwards or forwards by one Step. Can also be performed by typing
|
|
Control-b and Control-f from any window.<br>
|
|
</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">RT</span> Clicking this
|
|
button will synchronize XEphem to the computer clock and commence
|
|
Updating every Pause seconds. If Pause is 0 when this is started, it
|
|
will be set to 10 seconds. This can be the initial mode for XEphem by
|
|
saving the AutoRT <a href="xephem.html#MainMenu_preferences">Preference</a>.
|
|
RT is really just a shortcut for:<br>
|
|
<br>
|
|
<ol>
|
|
<li>clicking Now under the calendar</li>
|
|
<li>setting Step to Clock</li>
|
|
<li>setting N Steps to something large and then</li>
|
|
<li>clicking Update.</li>
|
|
</ol>
|
|
</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;"><img alt=""
|
|
src="png/stepsize.png" align="right" height="249" hspace="5" vspace="5"
|
|
width="297">Step</span> The interval by
|
|
which, or event to which, time is changed each loop. Fixed intervals
|
|
are
|
|
specified in hours, minutes, seconds, days and years or time may be set
|
|
to advance to an event such as the next sun rise, dawn or full moon.<br>
|
|
</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">N Steps</span> The number of
|
|
times the display will be updated (time advanced by Step each step)
|
|
automatically. When Update is clicked, this number counts down until it
|
|
reaches zero then is reset to one.<br>
|
|
</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Pause</span> Number of seconds
|
|
to
|
|
pause between screen Updates. This is used mainly to set up for
|
|
free-running unattended operation. Pausing is not done when <a
|
|
href="#Plot">plotting</a>,<a href="#Listing">listing</a> or <a
|
|
href="#Search">solving</a> are active. When looping, time is
|
|
maintained at a whole multiple of pause length.</li>
|
|
</ul>
|
|
When looping is in effect, the label on the bottom button changes to <span
|
|
style="font-weight: bold;">Stop</span>. When the number of steps
|
|
goes to 0 or the Stop button is clicked the looping stops and the
|
|
button label changes back to <span style="font-weight: bold;">Update.</span><br>
|
|
<br>
|
|
Note that when looping with Pause set to 0, most graphics and numeric
|
|
field data are not drawn in order to speed up the computations. These
|
|
values are always updated internally, however. and may safely be used
|
|
for <a href="#Plot">plotting</a>,<a href="#Listing">listing</a> and <a
|
|
href="#Search">solving</a>. This is true even if the window that
|
|
displays the information is closed.<br>
|
|
<h1><a class="mozTocH1" name="mozTocId705230"></a> 3.0 <span
|
|
style="font-weight: bold;">File menu</span></h1>
|
|
<h2><a class="mozTocH2" name="mozTocId795475"></a> 3.1 <span
|
|
style="font-weight: bold;"><a name="SysLog"></a>System log</span></h2>
|
|
<img alt="" title="" src="png/syslog.png" align="right" height="164"
|
|
hspace="20" width="500"> This window contains additional
|
|
information from XEphem. Whenever an entry is written the computer may
|
|
beep, depending on the setting of the <span style="font-weight: bold;">Log
|
|
bell</span> <a href="#MainMenu_preferences">Preference</a>. The
|
|
contents of all Alert windows are also written here. Scroll bars to the
|
|
right and below allow panning through the log.<br>
|
|
<br>
|
|
<span style="font-weight: bold;">Erase</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Permanently discards all log entries. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Close</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Closes the log window but has no
|
|
effect
|
|
on its contents or ability to capture further information. </div>
|
|
<h2><a class="mozTocH2" name="mozTocId557162"></a> 3.2 <b><a name="Gallery"></a>Gallery</b></h2>
|
|
<img alt="" title="" src="png/gallery.png" align="right" height="403"
|
|
hspace="20" width="567">This window is a portal to high quality
|
|
color images.<br>
|
|
<br>
|
|
The Gallery window is broken into three sections. Down the right side
|
|
is a scrolled list of the
|
|
available images. Images are displayed in the upper left, captions in
|
|
the lower left. All sections scroll
|
|
to accommodate large areas. A sash between the upper and lower
|
|
sections on the left allow you to control the proportion of vertical
|
|
space used by each. <br>
|
|
<br>
|
|
Controls across the bottom:<br>
|
|
<blockquote> </blockquote>
|
|
<b>Close</b><br>
|
|
<blockquote> Close the Gallery window. <br>
|
|
</blockquote>
|
|
<b>Rescan</b><br>
|
|
<blockquote> Reinitialize the list. This also occurs each time the
|
|
Gallery window is opened. <br>
|
|
</blockquote>
|
|
<b>Sky Point</b><br>
|
|
<blockquote> If the current XEphem database contains an object whose
|
|
name matches the Gallery object currently being displayed, this button
|
|
will
|
|
be active and clicking this button will center the object in the Sky
|
|
View.
|
|
</blockquote>
|
|
<h3><a class="mozTocH3" name="mozTocId895040"></a> 3.2.1 <b>File format</b></h3>
|
|
The Gallery database index is stored in one or more files with the
|
|
suffix <b>.gly</b>. The index files and the image files to which they
|
|
refer reside in a directory named <b>gallery</b> which in turn must
|
|
reside within either the <a href="#SharedPrivateDirs">Shared or Private</a>
|
|
directories. All index files found are combined and sorted by name into
|
|
the scrolled list.<br>
|
|
<br>
|
|
The index file is in XML format. The entire collection is within one
|
|
outer-most element named <tt>gallery</tt>. In turn it contains one
|
|
element named <tt>image</tt> for each
|
|
Gallery image file.
|
|
In turn it contains one or more elements named <tt>name</tt>, one
|
|
element named <tt>file</tt> and one element named <tt>description</tt>.
|
|
The file name is with respect to the directory in which the .gly file
|
|
resides. When XEphem reads the description contents, it replaces
|
|
isolated newlines with blanks so that word wrapping is left up to the
|
|
scrolled text window. Please refer to the following example.<br>
|
|
<blockquote>
|
|
<pre><gallery><br> <image><br> <name><br> NGC 4414<br> </name><br> <file><br> 1999-25-a-web_print.jpg<br> </file><br> <description><br>In 1995, the majestic spiral galaxy NGC 4414 was imaged by the Hubble<br>Space Telescope as part of the HST Key Project on the Extragalactic<br>Distance Scale. An international team of astronomers, led by Dr. Wendy<br>Freedman of the Observatories of the Carnegie Institution of Washington,<br>observed this galaxy on 13 different occasions over the course of<br>two months.<br><br>Image Credit: Hubble Heritage Team (AURA/STScI/NASA)<br> </description><br> </image><br></gallery><br> <br> <br></pre>
|
|
</blockquote>
|
|
<h2><a class="mozTocH3" name="mozTocId323368"></a> 3.3 <a name="NetSetup"></a>Network
|
|
Setup</h2>
|
|
<img style="width: 387px; height: 172px;" alt="" title=""
|
|
src="png/network-setup.png" align="right" hspace="20" vspace="0">This
|
|
window controls how XEphem tries to
|
|
connect to
|
|
the Internet. One of the following three choices must be turned on for
|
|
Internet access to be available.<br>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Direct connect</span> This
|
|
choice
|
|
just means to use the direct DNS/IP TCP/IP sockets as necessary. Use
|
|
this one unless you are behind a firewall.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">via Proxy</span> This choice
|
|
attempts to access the Internet via a Proxy. Type the port address
|
|
and the host name of the proxy in the fields provided.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">via SOCKS</span> This choice
|
|
attempts to access the Internet via a version 4 SOCKS server. Type
|
|
the port address and the host name of the server in the fields
|
|
provided. These values can be initialized using the environment
|
|
variables SOCKS_PORT and SOCKS_NS.</li>
|
|
</ul>
|
|
If your Proxy or SOCKS firewall require Authentication, turn on the <span
|
|
style="font-weight: bold;">Auth</span> option and enter name and
|
|
password in the fields provided. Note that only the Name field may be
|
|
Saved.<br clear="all">
|
|
<h2><a class="mozTocH3" name="mozTocId203018"></a> 3.4 <a
|
|
name="ExternalInput"></a>External Input</h2>
|
|
<img style="width: 236px; height: 101px;" alt="" title=""
|
|
src="png/external-input.png" align="right" hspace="20" vspace="10">XEphem
|
|
can read a file (or fifo)
|
|
containing sets of
|
|
time, latitude and longitude values and automatically install these
|
|
values sequentially unattended. Enter the name of the file in the
|
|
window
|
|
and press OK. To pause between updates, set the desired delay in the
|
|
Pause field of the Main window. All features of XEphem, such as <a
|
|
href="#Plot">plotting</a> and <a href="#Listing">listing</a> are
|
|
available while this feature is running.<br>
|
|
<br>
|
|
The format of each line of the file is as follows:<br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> <span style="font-family: monospace;">JD
|
|
Lat Long</span> </div>
|
|
<br>
|
|
where<br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> JD = Julian Date </div>
|
|
<div style="margin-left: 40px;"> Lat = Latitude, radians, +north<br>
|
|
Long = Longitude, radians, +west </div>
|
|
<br>
|
|
The fields are separated by one or more blanks or tabs. All lines not
|
|
having exactly three floating point values are ignored and may be used
|
|
for comments, etc.<br>
|
|
<br>
|
|
<h1><a class="mozTocH1" name="mozTocId792957"></a> 4.0 <span
|
|
style="font-weight: bold;">View menu</span></h1>
|
|
<a name="Data_Table"></a>
|
|
<h2><a class="mozTocH1" name="mozTocId764058"></a> 4.1 Data Table</h2>
|
|
<div style="text-align: left;">
|
|
<div style="text-align: center;"> <img
|
|
style="width: 570px; height: 217px;" alt="" title=""
|
|
src="png/data-table.png" hspace="20" vspace="15"> </div>
|
|
This is a table of information about each of the current <a
|
|
href="#Favorites">Favorites</a>. Each data item occupies one
|
|
column in the table and each object occupies one row. </div>
|
|
<br>
|
|
The Control pulldown menu contains the following options:<br>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Setup...</span> This button
|
|
brings up a configure window to specify the table rows and columns
|
|
as desired.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">List...</span> This button
|
|
allows the current data table to be saved in a text file.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">X Select</span>
|
|
This button puts the current contents of the data table into the X11
|
|
PRIMARY selection buffer. You can then typically paste it into a file
|
|
using the middle mouse button.<br>
|
|
</li>
|
|
</ul>
|
|
When any columns related to rising or setting are active a box at the
|
|
bottom will indicate whether the times refer to the center or the
|
|
upper limb of the object. Similarly, when either the RA or Dec columns
|
|
are active or any of the separation columns are active a box will be
|
|
present to indicate whether the separation is from a geocentric or
|
|
topocentric point of view. The box will also indicate the precession
|
|
epoch.<br>
|
|
<br>
|
|
Any of the information in this table may be <a href="#Plot">plotted,</a>
|
|
<a href="#Listing">listed</a> or used in a <a href="#Search">solver</a>
|
|
algorithm.<br>
|
|
<br>
|
|
<a name="DataSelection_Table"></a>
|
|
<h3><a class="mozTocH1" name="mozTocId121454"></a> 4.1.1 Data setup</h3>
|
|
<img alt="" src="png/data-table-setup.png" align="right" height="241"
|
|
hspace="10" width="297">This
|
|
window lets you configure which columns will be in the Data Table.
|
|
When this window first comes up it will be set to indicate the state
|
|
of the Data Table. You may then manipulate the toggle buttons as
|
|
desired. To actually change the Data Table to a new configuration
|
|
select the <span style="font-weight: bold;">Apply</span> button. <span
|
|
style="font-weight: bold;">Ok</span> does the same thing but also
|
|
closes this window. <span style="font-weight: bold;">Close</span> just
|
|
closes this window without making any permanent changes.<br>
|
|
<br>
|
|
Entries are grouped into three sections for clarity. Column one
|
|
controls miscellaneous basic information. The descriptions of each
|
|
entry are as follows:<br>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Cns</span> name of the
|
|
constellation in which the object appears.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">RA</span> Right ascension: if
|
|
Main Equinox is set to EOD this is the apparent place, otherwise it
|
|
is the astrometric (mean) place. If Main Preference Equatorial is
|
|
Topocentric, it is further corrected for parallax.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">HA</span> geocentric or
|
|
topocentric hour angle of object, computed as LST-RA precessed to
|
|
EOD. Positive angles are west of the meridian.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">GHA</span> Greenwich Hour Angle,
|
|
hour angle of object when at 0° longitude.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Dec</span> Declination: if Main
|
|
Equinox is set to EOD this is the apparent place, otherwise it is
|
|
the astrometric (mean) place. If Main Preference Equatorial is
|
|
Topocentric, it is further corrected for parallax.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Az</span> topocentric degrees
|
|
eastward of true north for object.<br>
|
|
<br>
|
|
</li>
|
|
<li><b>Alt</b> topocentric degrees up from a
|
|
horizontal plane that is Elevation feet above sea level. Corrected
|
|
for refraction.<br>
|
|
</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Zenith</span> topocentric Zenith
|
|
distance, degrees; corrected for refraction.<br>
|
|
<br>
|
|
</li>
|
|
<li><b>PA</b> parallactic angle, i.e., the angle as seen from the
|
|
target between zenith and NCP, measured positive westward of meridian.<br>
|
|
<br>
|
|
</li>
|
|
<li><b>JD</b> current UTC Julian date.<br>
|
|
<br>
|
|
</li>
|
|
<li><b>HJD</b> current heliocentric Julian date, i.e., JD adjusted to
|
|
time frame of Sun.<br>
|
|
</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Air</span> Number of relative
|
|
air masses through which light from the object passes to the
|
|
topocentric observer. Computed by the method of Hardie, clamped to a
|
|
max at 3 degrees altitude.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">VMag</span> visual magnitude
|
|
of object.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><b>PMRA</b> Proper Motion in RA. Units are arcseconds/hour for a
|
|
Solar system object, degrees/minute for an Earth satellite and
|
|
milliarcseconds/year for all other types of objects.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><b>PMDec</b> Proper Motoin in Declination. See PMRA for units.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Size</span> angular size of
|
|
object, in arc seconds. If not otherwise given, estimated for
|
|
objects in heliocentric orbits from the absolute magnitude parameter H
|
|
and by assuming an albedo of 0.10, for which H is 18 for an object
|
|
of 1.06 km diameter at 1.0 AU.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Phase</span> percent of visible
|
|
surface in sun light.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Elong</span> spherical angular
|
|
separation between the Sun and given object, calculated from the their
|
|
geocentric ecliptic coordinates. Note this is not just the
|
|
difference in ecliptic longitude, as is sometimes used. The sign is
|
|
positive for an evening object or negative for a morning object.
|
|
Thus, this field is not generally useful in searching for eclipses
|
|
because of the discontinuous sign change which occurs at
|
|
conjunction. For that, use the individual Separations fields.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Spect</span> Basic spectral
|
|
classification, if appropriate.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">HeLat</span> true heliocentric
|
|
latitude, in degrees. For the Moon this is the geocentric latitude.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">HeLong</span> true heliocentric
|
|
longitude, in degrees. Earth's is displayed on the Sun's line. For the
|
|
Moon this is the geocentric longitude.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">GLat</span> galactic latitude,
|
|
in
|
|
degrees. Based on 32.93192° longitude of ascending node on
|
|
equator, 192.85948° RA J2000 of North Galactic Pole and
|
|
27.12825° Declination of pole.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">GLong</span> galactic longitude,
|
|
in degrees. See GLat for definition.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">EcLat</span> ecliptic latitude,
|
|
in degrees.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">EcLong</span> ecliptic
|
|
longitude,
|
|
in degrees.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">EaDst</span> true distance from
|
|
Earth center to object center, in AU, except distance to the Moon is
|
|
in miles or km depending on the Units preference.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">EaLght</span> time for light
|
|
to travel from Earth to object. Format is hh:mm for all solar system
|
|
objects, except the Moon is in decimal seconds.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">SnDst</span> true distance from
|
|
Sun center to object center, in AU.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">SnLght</span> time for light
|
|
to travel from Sun to object. Format is hh:mm.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Uranom</span> Volume and Page
|
|
number of object's location in the original Uranometria, published
|
|
by Willmann-Bell, Inc.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Uran2k</span> Volume and Page
|
|
number of object's location in the new Uranometria 2000 edition.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">MillSA</span> Volume and Page
|
|
number of object's location in the Millenium Star Atlas, published
|
|
by Sky Publishing Corp.</li>
|
|
</ul>
|
|
Section two controls information related to rising, transitting, and
|
|
setting. These are computed based on a refraction model that uses the
|
|
actual atmospheric and topocentric circumstances displayed on the Main
|
|
window. A text entry field is available in which you may specify a
|
|
number of decimal degrees the local horizon is above horizontal to
|
|
account for local effects.<br>
|
|
<br>
|
|
The <span style="font-weight: bold;">Limb</span> option means that
|
|
the rise and set circumstances are based on the location of the upper
|
|
limb of the object. <span style="font-weight: bold;">Center</span>
|
|
means
|
|
that the circumstances are based on the location of the center of the
|
|
object.<br>
|
|
<br>
|
|
Follows is a description of the Data Table columns controlled by the
|
|
second Data Selection section:<br>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">RisTm</span> and <span
|
|
style="font-weight: bold;">RisAz</span> The local or UTC time and
|
|
azimuth when the upper limb (or center) of the object rises Today.
|
|
See note below for Earth satellites.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">TrnTm</span>,
|
|
<span style="font-weight: bold;">TrnAlt</span> and
|
|
<span style="font-weight: bold;">TrnAz</span>
|
|
For all but Earth
|
|
satellites, this is the local or UTC time, altitude and azimuth when
|
|
the object crosses the meridian Today or, if no precession, when the
|
|
local sidereal time equals the object's right ascension.
|
|
If the object is an Earth satellite, this is the next time, highest
|
|
altitude and corresponding azimuth the satellite ever reaches above the local
|
|
horizon.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">SetTm</span> and <span
|
|
style="font-weight: bold;">SetAz</span> The local or UTC time and
|
|
azimuth when the upper limb (or center) of the object sets Today.
|
|
See note below for Earth satellites.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">HrsUp</span> The number of hours
|
|
the object is up Today, that is, the difference between the set and
|
|
rise times. See note below for Earth satellites.<br>
|
|
</li>
|
|
</ul>
|
|
Note for time zones:<br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Rise and set circumstances are all
|
|
computed in local time. If the Zone Display preference (from the
|
|
Main menubar) is set to UTC then the times are converted to UTC.
|
|
Thus, when reference is made to Today it means the current local
|
|
date, not UTC date. </div>
|
|
<br>
|
|
Note for Earth satellites:<br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Due to their generally rapid motions
|
|
Earth satellites often have many rising and setting events per day.
|
|
For this reason, the rise and set time for satellites are not
|
|
restrained to be during the current local day. Rather, for
|
|
satellites, XEphem displays the very next rising and setting events
|
|
that occur strictly later than the current time on the Main window,
|
|
provided they occur within 24 hours. This means that if the rise or
|
|
set time displayed is earlier than the current local time on the
|
|
Main window, it actually refers to the next day. This doesn't happen
|
|
for the other objects because their times are restricted to events
|
|
that happen just today. Similarly, we can only compute the HrsUp
|
|
column if the set time is strictly later than the rise time.<br>
|
|
<br>
|
|
The upshot of all this is that the best way to really understand
|
|
the visibility of a satellite in your area is by graphing its
|
|
altitude over the desired time interval, or displaying all its
|
|
passes in the Night-at-a-Glance tool. </div>
|
|
<br>
|
|
Various odd ball rising, transit and setting conditions are accounted
|
|
for and marked when they occur as in the following table. Note that in
|
|
the case of Earth satellites, "Today" really means within the next 24
|
|
hours.<br>
|
|
<br>
|
|
<table
|
|
style="text-align: left; margin-left: auto; margin-right: auto; width: 75%;"
|
|
summary="oddball rise/set situations" border="0" cellpadding="2"
|
|
cellspacing="2">
|
|
<tbody>
|
|
<tr>
|
|
<td><span style="font-weight: bold;">NoRise</span></td>
|
|
<td>up some time but never rises, as such, Today.</td>
|
|
</tr>
|
|
<tr>
|
|
<td><span style="font-weight: bold;">NoSet</span></td>
|
|
<td>up some time but never sets, as such, Today.</td>
|
|
</tr>
|
|
<tr>
|
|
<td><span style="font-weight: bold;">NoTran</span></td>
|
|
<td>up some time but doesn't transit, as such, Today.</td>
|
|
</tr>
|
|
<tr>
|
|
<td><span style="font-weight: bold;">CirPol</span></td>
|
|
<td>object is circumpolar (never goes below horizon) Today.</td>
|
|
</tr>
|
|
<tr>
|
|
<td><span style="font-weight: bold;">NvrUp</span></td>
|
|
<td>object is never above the horizon Today.</td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
<br>
|
|
The third section in the Data Table setup window lists the current
|
|
set of <a href="#Favorites">Favorites</a>. Any one may be selected
|
|
for which the angular separation between it and the object on that row
|
|
will be shown, in degrees.<br>
|
|
<br>
|
|
The vantage point for the Separation values depends on the Equatorial <a
|
|
href="#MainMenu_preferences">preference</a> in the Main window.
|
|
Geocentric ignores local conditions and gives the separation as seen
|
|
from Earth center. Topocentric uses the local conditions known to
|
|
XEphem. The choice is particularly critical for lunar occultations and
|
|
Earth satellites, of course, but the effect can be significant for the
|
|
planets as well. Geocentric separations between objects and the Sun
|
|
will match the magnitude of the elongation given in the Data Table
|
|
window.<br>
|
|
<br>
|
|
Note:<br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Solving over a period that will
|
|
include
|
|
the rise or set times of either object is generally better performed
|
|
from the geocentric viewpoint. The refraction effect of the
|
|
topocentric viewpoint causes many arc minutes of rapid whiplash
|
|
displacement as the objects rise and set that overlays the smooth
|
|
celestial motion of the objects. This rapid position variation can
|
|
confuse the solver algorithms that expect fairly smooth functions.<br>
|
|
</div>
|
|
|
|
<h2><a class="mozTocH2" name="mozTocId576774"></a> 4.2 <a name="Sun"></a>Sun</h2>
|
|
<img alt="" src="png/sun-view.png" align="right" height="324"
|
|
hspace="10" width="266">This
|
|
window provides a convenient tool to download, display and manage
|
|
images
|
|
from SOHO, the <a target="_blank"
|
|
href="http://sohowww.nascom.nasa.gov/">Solar
|
|
& Heliospheric Observatory</a>. <font size="3">Use of this
|
|
extraordinary data is courtesy of the SOHO consortium. SOHO is a
|
|
project
|
|
of international cooperation between ESA and NASA.<br>
|
|
<br>
|
|
The SOHO data is pulled from the web site
|
|
http://sohowww.nascom.nasa.gov. The host name is defined in the XEphem
|
|
resource XEphem.SOHOhost. This may be changed if necessary by placing a
|
|
new value in the XEphem resource file.<br>
|
|
</font>
|
|
<h3><a class="mozTocH3" name="mozTocId591361"></a> 4.2.1 Sun mouse</h3>
|
|
Moving the mouse over a loaded SOHO image will display the approximate
|
|
RA and Dec under the cursor. To do this XEphem makes an assumption
|
|
about
|
|
the scale and orientation of the image and defines the center of the
|
|
image as the position of the sun computed at the current XEphem time.
|
|
However, we have found SOHO images are not always oriented the same way
|
|
and we are not aware of a means to know the orientation
|
|
programmatically
|
|
so beware. The Carrington Rotation Number is shown in the lower right,
|
|
also as of the current XEphem time. If XEphem time differs from when
|
|
the
|
|
SOHO image was acquired the coordinates will still be correct but of
|
|
course the solar features shown in the image will not be correct. <br>
|
|
<br>
|
|
Note that the coordinates do not take account of the different
|
|
perspective from the SOHO spacecraft. SOHO does not wander far from the
|
|
Sun-Earth line so images of the sun itself do not suffer much but this
|
|
effect is quite pronounced for Large Angle and Spectrometric
|
|
Coronagraph
|
|
images where the coordinates of background objects may be off by a
|
|
degree or more. Again, beware and check all coordinates independently
|
|
for important work.<br>
|
|
<h3><a class="mozTocH3" name="mozTocId950828"></a> 4.2.2 <span
|
|
style="font-weight: bold;">Sun Control menu<br>
|
|
</span></h3>
|
|
<span style="font-weight: bold;">Download latest<br>
|
|
</span>
|
|
<div style="margin-left: 40px;"><br>
|
|
Clicking this entry will use your <a href="#NetSetup">Internet</a>
|
|
connection to download the latest image from SOHO. The type and size of
|
|
the downloaded image are determined by the current selections in the
|
|
Type and Size menus.<br>
|
|
<br>
|
|
</div>
|
|
<span style="font-weight: bold;">Save downloaded image<br>
|
|
</span>
|
|
<div style="margin-left: 40px;"><br>
|
|
This button is active only if the currently displayed image was
|
|
downloaded from the net and has not yet been saved. Clicking this
|
|
button will save the
|
|
downloaded SOHO image currently being displayed to the
|
|
<a href="#SharedPrivateDirs">Private</a> XEphem directory in .gif
|
|
format.
|
|
The name of the file always begins with SOHO and includes the size,
|
|
date, time
|
|
and code name of the data product. For example, the following file name:<br>
|
|
<div style="margin-left: 40px;"><span style="font-family: monospace;"><br>
|
|
SOHO_512_20030802_0100_eit_171.gif<br>
|
|
</span><br>
|
|
</div>
|
|
</div>
|
|
<div style="margin-left: 40px;">indicates the file is 512x512, was
|
|
acquired 2003 Aug 02 at 01:00 UTC and is from the 171Å channel of
|
|
the Extreme ultraviolet Imaging Telescope.<br>
|
|
<br>
|
|
</div>
|
|
<span style="font-weight: bold;">Filter Files by Type<br>
|
|
Filter Files by Size<br>
|
|
<span style="font-weight: bold;"><br>
|
|
</span></span>
|
|
<div style="margin-left: 40px;">These options control whether the files
|
|
presented by the Files menu will be filtered by the current setting of
|
|
the Type menu or the Size menu, respectively. If a filter is not
|
|
selected then all files found will be listed.<br>
|
|
<br>
|
|
</div>
|
|
<span style="font-weight: bold;">Print...</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This selection allows printing the
|
|
current SOHO view or saving it to a file. See <a href="#Print">Printing</a>.</div>
|
|
<br>
|
|
<span style="font-weight: bold;">User annotation...</span><br>
|
|
<blockquote>This selection brings up a window
|
|
which
|
|
allows text and lines to be drawn over the SOHO image. See <a
|
|
href="xephem.html#Annotation">Annotation</a>.<br>
|
|
</blockquote>
|
|
<b>Add to movie...</b><br>
|
|
<blockquote>This selection brings up a window to allow adding the
|
|
current Sun view to a <a href="#Movie">movie loop</a>.<br>
|
|
</blockquote>
|
|
<h3><a class="mozTocH3" name="mozTocId141077"></a> 4.2.3 Sun Files menu<br>
|
|
</h3>
|
|
This menu lists each of the SOHO image files currently found
|
|
in either the Private or Shared directories. Depending on the Filter
|
|
settings in the Control menu it will list all
|
|
images or just those that match the current setting of the Type or Size
|
|
menus.
|
|
Selecting a file from the list will display it in this window.<br>
|
|
<h3><a class="mozTocH3" name="mozTocId156397"></a> 4.2.4 <span
|
|
style="font-weight: bold;">Sun Type menu<br>
|
|
</span></h3>
|
|
<span style="font-weight: bold;"></span>This menu lists each of the
|
|
eight data products provided by SOHO, one of which may be selected at a
|
|
time. The type selected here will be used when Downloading a file from
|
|
the Control menu, and may also limit the scope of files listed by the
|
|
Files menu if the Filter option is On in the Control menu. Follows is a
|
|
brief summary of the data product referenced by each menu entry.<br>
|
|
<br>
|
|
<br>
|
|
<table style="text-align: left; width: 100%; margin-left: 40px;"
|
|
border="0" cellpadding="2" cellspacing="2">
|
|
<tbody>
|
|
<tr>
|
|
<th style="vertical-align: top;">Menu Entry<br>
|
|
</th>
|
|
<th style="vertical-align: top;">Instrument</th>
|
|
<th style="vertical-align: top;">Notes</th>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top;">EIT 171 </td>
|
|
<td style="vertical-align: top;">Extreme ultraviolet Imaging
|
|
Telescope</td>
|
|
<td style="vertical-align: top;">Fe IX/X 171 Å, rendered
|
|
blue</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top;">EIT 195 </td>
|
|
<td style="vertical-align: top;"><br>
|
|
</td>
|
|
<td style="vertical-align: top;">Fe XII 195 Å, rendered
|
|
green</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top;">EIT 284</td>
|
|
<td style="vertical-align: top;"><br>
|
|
</td>
|
|
<td style="vertical-align: top;">Fe XV 284 Å, rendered
|
|
yellow</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top;">EIT 304</td>
|
|
<td style="vertical-align: top;"><br>
|
|
</td>
|
|
<td style="vertical-align: top;">He II 304 Å, rendered
|
|
orange</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top;">HMI Continuum</td>
|
|
<td style="vertical-align: top;">Helioseismic and Magnetic Imager</td>
|
|
<td style="vertical-align: top;">Visible Sun spots<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top;">HMI Magnetogram </td>
|
|
<td style="vertical-align: top;"><br>
|
|
</td>
|
|
<td style="vertical-align: top;">Magnetic Sun spots<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top;">LASCO C2</td>
|
|
<td style="vertical-align: top;">Large Angle and Spectrometric
|
|
Coronagraph</td>
|
|
<td style="vertical-align: top;">Corona to 6 solar radii<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top;">LASCO C3</td>
|
|
<td style="vertical-align: top;"><br>
|
|
</td>
|
|
<td style="vertical-align: top;">Corona to 3 solar radii<br>
|
|
</td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
<br>
|
|
<h3><a class="mozTocH3" name="mozTocId660536"></a> 4.2.5 <span
|
|
style="font-weight: bold;">Sun Size menu</span></h3>
|
|
This menu lists each of the three file sizes of images provided by
|
|
SOHO, one of which may be selected at a time. The size selected here
|
|
will be used when Downloading a file from the Control menu.
|
|
<div style="margin-left: 40px;"><br>
|
|
</div>
|
|
|
|
<a name="Moon"></a>
|
|
<h2><a class="mozTocH2" name="mozTocId427392"></a> 4.3 Moon</h2>
|
|
<img src="png/moon.png" alt="" align="right" height="350" hspace="10"
|
|
vspace="10" width="511">This
|
|
is
|
|
an image of the Moon, shaded to indicate phase. It may be flipped and
|
|
scaled as desired and many Lunar features may be labeled, including
|
|
most spacecraft landing sites. During a Lunar eclipse, the edges of
|
|
the umbra and penumbra regions are drawn as solid and dashed lines,
|
|
respectively.<br>
|
|
<br>
|
|
The coordinate system on the Moon is such that latitude increases
|
|
towards the north and longitude increases towards the east. When facing
|
|
the Moon with the unaided eye, lunar east is towards the right. The
|
|
lunar image in XEphem is oriented with the polar axis vertical on the
|
|
screen. Letters are placed at each edge of the image to show lunar
|
|
coordinate directions.<br>
|
|
<br>
|
|
The scrolling list on the right lists all features in the data base.
|
|
Clicking on a name will toggle its label on the map. The labels are
|
|
positioned so the center of the feature is at the lower left corner of
|
|
the label string. If the label is being turned on then the Labels View
|
|
option is also turned on if it is off.
|
|
Double-clicking will display the set of Lunar Orbiter images that
|
|
include the feature.<br>
|
|
<br>
|
|
The Moon nods and rocks slightly as it moves through the sky. This
|
|
motion is called libration. A dot is placed on the circumference of
|
|
the image to indicate the limb position that is currently tilted most
|
|
towards Earth due to libration. The angular position of the dot is
|
|
placed accurately but the image rendering is not adjusted for
|
|
libration effects. Thus, the surface features over which the dot and
|
|
the terminator appear in the image are only approximate.<br>
|
|
<a name="Moon_mouse"></a>
|
|
<h3><a class="mozTocH1" name="mozTocId423766"></a> 4.3.1 Moon mouse</h3>
|
|
<span style="font-weight: bold;">Left button</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Activating the left mouse button while
|
|
over the lunar image will display a small magnified 2x view of the
|
|
lunar surface under the cursor. The magnified image will track the
|
|
cursor as it is moved around the image. The latitude, longitude and
|
|
solar altitude of the location are displayed in the <span
|
|
style="font-weight: bold;">More info...</span> window. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Right button</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;">Activating the right mouse button while
|
|
over the lunar image will display a popup menu. It lists the name of
|
|
the
|
|
feature nearest to the cursor, the type, lunar coordinates and the
|
|
altitude of the sun as seen from that feature at the current XEphem
|
|
time. A toggle button <span style="font-weight: bold;">Label</span>
|
|
turns on or off a label on the map. A
|
|
pushbutton <span style="font-weight: bold;">Set info table</span>
|
|
loads the feature into the More info window and
|
|
will display window if it is not already up. If the Lunar Orbiter
|
|
database has been loaded, then a pushbutton <span
|
|
style="font-weight: bold;">Lunar Orbiter image</span> displays the
|
|
image in which this feature lies, and also turns on the feature's label
|
|
on the main map for handy reference.<br>
|
|
</div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Activating the right mouse button
|
|
while
|
|
not over the lunar image but near a sky background object will pop
|
|
up a menu containing the name and magnitude of the object. There
|
|
will also be a button <span style="font-weight: bold;">Add to favorites</span>
|
|
to assign the object to your <a href="#Favorites">Favorites</a>.</div>
|
|
<br>
|
|
The two features may be activated together if desired by first pressing
|
|
the left button then the right button. This is helpful when trying to
|
|
locate a particular feature in the magnified view. Try to always
|
|
release the right button to dismiss the popup before releasing the
|
|
left button. If you release the left button first, the magnifying
|
|
glass will remain on the image. If you run into this, you can activate
|
|
the glass again and mop up the remains of the old glass. <a
|
|
name="Moon_control"></a>
|
|
<h3><a class="mozTocH1" name="mozTocId691644"></a> 4.3.2 Moon Control menu</h3>
|
|
<span style="font-weight: bold;">Print...</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This selection allows printing the
|
|
current Moon view or saving it to a file. See <a href="#Print">Printing</a>.</div>
|
|
<br>
|
|
<span style="font-weight: bold;">User annotation...</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This selection brings up a window
|
|
which
|
|
allows text and lines to be drawn over the image. See <a
|
|
href="#Annotation">Annotation</a>. </div>
|
|
<br>
|
|
<b>Add to movie...</b><br>
|
|
<blockquote>This selection brings up a window to allow adding the
|
|
current Moon view to a <a href="xephem.html#Movie">movie loop</a>.<span
|
|
style="font-weight: bold;"><br>
|
|
</span></blockquote>
|
|
<span style="font-weight: bold;">Field Stars...</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This selection activates the Field
|
|
Star
|
|
setup window. See <a href="#FieldStars">Field stars</a>. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Set Earthshine...</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This brings up a window containing a
|
|
scale which allows you to set how bright the Earthshine is in the
|
|
Moon image. The value ranges from 0, black, to 10, full sun light.
|
|
Full sun light is useful when you would like to peruse the Lunar
|
|
surface but would rather not change the XEphem date to a full Moon.<br>
|
|
<br>
|
|
This value depends on the gamma of your display. A fine discussion
|
|
of display gamma and a test image with which you can determine the
|
|
gamma value of your own display may be found at the URL: <a
|
|
href="http://web.mit.edu/jmorzins/www/gamma/rwb/gamma.html"
|
|
target="new">http://web.mit.edu/jmorzins/www/gamma/rwb/gamma.html</a>.</div>
|
|
<br>
|
|
<span style="font-weight: bold;">Movie Demo</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This button sets up an automatic
|
|
display
|
|
movie
|
|
of the Moon. This is done by setting the N Steps entry in the Main
|
|
window to a large value; setting the Step to two hours if Sky
|
|
background is Off or to one minute if it is On; and starting XEphem <a
|
|
href="#main_looping">looping</a>. The movie can be stopped by
|
|
selecting this option again or by selecting Stop from the Main window. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Forget labels</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;">This button forgets the labels that
|
|
have been added either via the popup or the list to the right. Note
|
|
this is different than turning off labels in the View menu, which only
|
|
temporarily turns of the labels but does not forget.<br>
|
|
</div>
|
|
<br>
|
|
<span style="font-weight: bold;">Close</span><br
|
|
style="font-weight: bold;">
|
|
<br>
|
|
<div style="margin-left: 40px;"> This closes the main Moon display and,
|
|
if open, the More info window. The image is never updated while it
|
|
is closed. however if any of the fields in the More Info window are
|
|
being used for <a href="#Plot">plotting</a>,<a href="#Listing">listing</a>
|
|
or <a href="#Search">solving</a>, they continue to be updated even
|
|
when
|
|
the window is closed. <a name="Moon_view"></a> </div>
|
|
<h3><a class="mozTocH1" name="mozTocId946969"></a> 4.3.3 Moon View menu</h3>
|
|
<span style="font-weight: bold;">Spacecraft</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> If set and the Scale is at 6, then all
|
|
spacecraft landing sites are marked and labeled on the image. If the
|
|
Scale is less than 6, then only the Apollo sites are marked. </div>
|
|
<b><br>
|
|
Labels</b><span style="font-weight: bold;"></span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This sets whether additional
|
|
(non-spacecraft) Lunar features may be labeled on the image. Exactly
|
|
which ones are labeled is controlled from the scrolled list down the
|
|
right or with the popup menu activated by the right mouse button. Note
|
|
that turning labels off with this button does not forget which features
|
|
are labeled, it only turns them off. To actually forget the labels, use
|
|
the Undo labels button in the Control menu.<br>
|
|
</div>
|
|
<br>
|
|
<span style="font-weight: bold;">Sky background</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This sets whether to show objects
|
|
within the current field of view that are in the XEphem database
|
|
memory or available from the Field Star facility. The size and
|
|
symbol used for the object matches that of the Sky view when set for
|
|
a minimum magnitude of 12. While this option is on, XEphem will
|
|
automatically retrieve field stars if the moon position changes on
|
|
the sky </div>
|
|
<br>
|
|
<span style="font-weight: bold;">{Pen}Umbra</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This sets whether to show circles at
|
|
the edges of the umbra and penumbra during a Lunar eclipse.
|
|
Also, the current subearth location is marked with an X; the
|
|
subsolar point is marked with a small open circle; and the
|
|
anti-subsolar point is marked with a small filled circle. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Flip T/B</span><br>
|
|
<span style="font-weight: bold;">Flip L/R</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> These set whether the image is flipped
|
|
vertically or horizontally, respectively. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Grid</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This sets whether a coordinate grid is
|
|
drawn over the image. Each line is spaced at an interval of 15
|
|
degrees. </div>
|
|
<h4><a class="mozTocH3" name="mozTocId868643"></a> 4.3.3.1 <img
|
|
style="width: 191px; height: 387px;" alt="" title=""
|
|
src="png/moon-more-info.png" align="right" hspace="20">More info...</h4>
|
|
<div style="margin-left: 40px;"> This brings up a separate window with
|
|
additional information. The top portion of the window reports the
|
|
location of the cursor as it is moved over the image, if the left
|
|
button is pressed. It also shows the altitude of the Sun and the
|
|
times when the Sun will next rise and set at that location. The times
|
|
are in accord with the Time zone <a href="#MainMenu_preferences">Preferences</a>
|
|
in the Main window.<br>
|
|
<br>
|
|
The lower portion of the window shows the lunar longitude of sunrise,
|
|
the lunar latitude of the subsolar point, and libration information.
|
|
The longitude of the subsolar point is at +90 from the sunrise
|
|
longitude, and the longitude of the anti-subsolar point is at -90.
|
|
The libration in longitude is positive towards lunar east; latitude
|
|
is positive towards lunar north. The Limb angle is zero at lunar
|
|
north and increases towards lunar west. The Tilt is the number of
|
|
degrees the Moon is tilted towards Earth around an axis defined by
|
|
the librations in latitude and longitude. The limb location that is
|
|
tilted most towards Earth is indicated on the image by a small dot.<br>
|
|
<br>
|
|
Any of the values in the lower portion may be <a href="#Plot">plotted,</a>
|
|
<a href="#Listing">listed</a> or used in a <a href="#Search">solver</a>
|
|
algorithm. The values are always current when used in this way, even
|
|
if the main Moon view is closed. For faster looping, close the main
|
|
Moon display to prevent it from being redrawn each time.<br clear="all">
|
|
</div>
|
|
<div style="margin-left: 40px;"> <a name="Moon_scale"></a> </div>
|
|
<h3><a class="mozTocH1" name="mozTocId218379"></a> 4.3.4 Scale menu</h3>
|
|
This pulldown menu presents a list of factors by which the lunar
|
|
image may be scaled. The image is presented in a scrolled window for
|
|
panning if it is larger than the overall window.<br clear="all">
|
|
<h3><a name="mozTocId832160" class="mozTocH3"></a> 4.3.5 <a name="Moon_lo"></a>Lunar
|
|
Orbiter IV</h3>
|
|
<img src="png/lo.png" alt="" align="right" height="423" hspace="10"
|
|
vspace="10" width="369">XEphem optionally supports displaying images
|
|
taken by Lunar
|
|
Orbiter IV in 1967. These images and the features database are used by
|
|
permission of
|
|
the Lunar and Planetary Institute.<br>
|
|
<br>
|
|
Lunar Orbiter images are located in the <span
|
|
style="font-family: monospace;">lo</span> directory within the Shared
|
|
directory. When these images are installed they are accessible from the
|
|
Moon view in two ways. One is to double-click an entry in the features
|
|
list down the right of the Moon view window. The other is to use the
|
|
Lunar Orbiter images button in the popup over the image in the main
|
|
Moon window. These functions are automatically disabled if XEphem
|
|
can not fund the images on startup.<br>
|
|
<br>
|
|
The LO images are displayed in their own window. The images are large
|
|
so panning controls are available on the bottom and right edges. The
|
|
annotation
|
|
overlay may be toggled on and off with the given toggle button. A
|
|
scrolled list in the lower right corner allows choosing one from among
|
|
all the LO images which contain the current feature.<br>
|
|
<br>
|
|
The LO images are not perfectly aligned NSEW, some are canted as much
|
|
as 30 degrees from vertical. The images are shown exactly as they were
|
|
taken. No attempt is made to register the images with the main
|
|
XEphem moon view, nor to perform flipping or scaling. The ability to
|
|
click to see the next adjacent image would have been nice but certain
|
|
technical difficulties made the results unsatisfactory and was left
|
|
out.<br>
|
|
<br>
|
|
The image scale is approximately 300m/pixel.<br>
|
|
<br clear="all">
|
|
<br>
|
|
<br>
|
|
<a name="Earth"></a>
|
|
<h2><a class="mozTocH1" name="mozTocId91149"></a> 4.4 Earth</h2>
|
|
<img alt="" src="png/earth.png" align="right" height="359"
|
|
hspace="10" vspace="10" width="348">This
|
|
view displays a view of the Earth with either schematic continent
|
|
outlines or a real color image. The night side may be dark or include
|
|
nightside lights. The projection may be spherical or
|
|
cylindrical "Mission Control" style. The controls available from the
|
|
menu bar across the top control the view, the display of additional
|
|
information and
|
|
the ability to overlay the ground positions of all Favorite objects.
|
|
The scales along the bottom and right edges display, and may be used
|
|
to control, the center longitude and latitude location. The button in
|
|
the lower right corner sets the latitude to exactly zero. The scale
|
|
along the left edge sets the zoom.<br>
|
|
<br>
|
|
Any or all of the current <a href="#Favorites">Favorites</a> may be
|
|
displayed on the map. Objects with defined date ranges are only shown
|
|
when they are valid. The location defined in the Main window is marked
|
|
on the map
|
|
with a plus (+).<br>
|
|
<br>
|
|
If a solar eclipse is occurring on the Earth a small X will mark the
|
|
location of central totality. Try July 11, 1991 around 18:00 UT or May
|
|
10, 1994 around 16:00 UT.<br>
|
|
<br>
|
|
All computations for Earth satellites are based on the NORAD SGP4/SDP4
|
|
code. This code produces the exact same output as their test
|
|
collection.
|
|
This means, however, that it is not integrated particularly tightly
|
|
with
|
|
the rest of XEphem. For example, its computations use a different model
|
|
for Earth flattening and for refraction. These and other differences
|
|
can
|
|
lead to modest inconsistencies. <a name="Earth_mouse"></a>
|
|
<h3><a class="mozTocH1" name="mozTocId320902"></a> 4.4.1 Earth mouse</h3>
|
|
As long as the cursor is over the Earth, the four corners of the View
|
|
will display the following information about the position beneath the
|
|
cursor:<br>
|
|
<br>
|
|
<table
|
|
style="text-align: left; width: 50%; margin-left: auto; margin-right: auto;"
|
|
summary="earth cursor info" border="0" cellpadding="2" cellspacing="2">
|
|
<tbody>
|
|
<tr>
|
|
<td style="vertical-align: top;">Upper left<br>
|
|
</td>
|
|
<td style="vertical-align: top;">Latitude and longitude<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top;">Upper right<br>
|
|
</td>
|
|
<td style="vertical-align: top; text-align: left;"> Great circle bearing and distance<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top;">Lower left<br>
|
|
</td>
|
|
<td style="vertical-align: top;">Local Mean Time<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top;">Lower right<br>
|
|
</td>
|
|
<td style="vertical-align: top;">Local Sidereal Time<br>
|
|
</td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
|
|
<div style="text-align: center;"></div>
|
|
<span style="font-weight: bold;">Left button</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;">
|
|
While the left button is depressed and located over the
|
|
Earth map, the great circle from the Main site location through the
|
|
cursor location will be drawn. </div>
|
|
<br>
|
|
|
|
<div style="text-align: center;"></div>
|
|
<span style="font-weight: bold;">Middle button</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> If <span
|
|
style="font-family: monospace;">View » Live dragging</span>
|
|
is On then while the middle button is depressed and located over the
|
|
Earth map, the cursor is changed to a fleur pattern. Moving the
|
|
mouse left and right is like sliding the scale at the bottom; moving
|
|
it up and down is like sliding the scale at the right. This provides
|
|
a simple method to pan the display. </div>
|
|
<br>
|
|
|
|
<span style="font-weight: bold;">Right button</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> If the right mouse button is clicked
|
|
while over the Earth, a popup menu appears with information related
|
|
to the location under the cursor. </div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> If the location is near a Site,
|
|
information is presented with respect to the exact location of that
|
|
site. </div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> If the location is not near a Site,
|
|
the
|
|
information is with respect to the latitude and longitude of the
|
|
location under the cursor. </div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> If the location is near the current or
|
|
a trailed location of one of the displayed objects either on the
|
|
surface or in orbit, the information
|
|
is with respect to the location of that object at the time of the
|
|
trail mark. </div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> There will also be a button labeled
|
|
Point that will center the orientation on the cursor location. <a
|
|
name="Earth_control"></a> </div>
|
|
<h3><a class="mozTocH1" name="mozTocId235796"></a> 4.4.2 Earth Control menu</h3>
|
|
<span style="font-weight: bold;">Print...</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This selection allows printing the
|
|
current Earth view or saving it as a Postscript file. See <a
|
|
href="#Print">Printing</a>. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">User annotation...</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This selection brings up a window
|
|
which
|
|
allows text and lines to be drawn over the image. See <a
|
|
href="#Annotation">Annotation</a>. </div>
|
|
<br>
|
|
<b>Add to movie...</b><br>
|
|
<blockquote>This selection brings up a window to allow adding the
|
|
current Earth view to a <a href="xephem.html#Movie">movie loop</a>.<span
|
|
style="font-weight: bold;"><br>
|
|
</span></blockquote>
|
|
<span style="font-weight: bold;">Objects...</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This brings up a table for controlling
|
|
how each current Favorite object is displayed. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Set Main<br>
|
|
<br>
|
|
</span>
|
|
<div style="margin-left: 40px;"> This sets the Latitude and Longitude
|
|
of
|
|
the Main window to that of the current position of the Earth view.
|
|
This also causes all other information and views to be updated to
|
|
reflect the new location. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Set From Main</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This sets the Earth view position to
|
|
that of the Main window </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Movie Demo</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This sets up an automatic display
|
|
movie
|
|
of the Earth. This is done by setting the N Steps entry in the Main
|
|
window to a large value; setting the Step to 5 minutes; and starting
|
|
XEphem <a href="#main_looping">looping.</a> The movie can be stopped
|
|
by
|
|
selecting this option again or by selecting Stop from the Main
|
|
window. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Close</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This causes both the Earth view and
|
|
the
|
|
extra statistics window to be closed. <a name="Earth_view"></a> </div>
|
|
<h3><a class="mozTocH1" name="mozTocId316841"></a> 4.4.3 Earth View menu</h3>
|
|
<span style="font-weight: bold;">Cylindrical graphic<br>
|
|
Cylindrical image<br>
|
|
</span><br>
|
|
<div style="margin-left: 40px;"> Displays the entire Earth surface
|
|
projected onto a cylinder. Primary advantage is the entire surface
|
|
is visible at once. Particularly good for plotting satellite ground
|
|
tracks. Major disadvantage is distortion near the poles. The
|
|
preferred width-to-height ratio for the cylindrical projection is
|
|
3.14:1. This ratio is enforced each time this projection is selected by
|
|
changing the width and maintaining the current window height, subject
|
|
to
|
|
remaining fully on screen. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Spherical graphic<br>
|
|
Spherical image<br>
|
|
<br>
|
|
</span>
|
|
<div style="margin-left: 40px;"> Displays the Earth as it would really
|
|
appear from space. The primary advantage is the sense of reality and
|
|
lack of distortion. Either projection may be shown using a simple
|
|
graphical technique which draws only the outlines of the major land
|
|
features, or using a full color image, courtesy NASA's project Blue
|
|
Marble. The former is fast, the latter looks much better. The spherical
|
|
projection resizes to become a square by setting the width equal to the
|
|
height. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Weather map</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Displays a global montage of satellite
|
|
cloud imagery, ice, sea and land temperatures, courtesy Space
|
|
Science and Engineering Center at the University of Wisconsin. The
|
|
image is a gif file retrieved from <a
|
|
href="http://www.ssec.wisc.edu/data/comp/latest_cmoll.gif" target="new">http://www.ssec.wisc.edu/data/comp/latest_cmoll.gif</a>.
|
|
It is updated once every six hours. All other graphical features of
|
|
the Earth view remain available as overlays to this image. Primary
|
|
advantage is ease in determining whether weather will effect
|
|
visibility of a satellite pass. If you have trouble accessing the
|
|
image directly from XEphem, the program will also use the file
|
|
/tmp/latest_cmoll.gif if it exists. The weather map forces itself to
|
|
become 640x480 pixels.<br>
|
|
<br>
|
|
After any projection is selected, the window size may be directly
|
|
manipulated manually from then on as desired. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Reload map</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This button is only present when the
|
|
Weather map projection is turned on. Pressing it will cause a fresh
|
|
weather map to be retrieved. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Grid</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This toggles showing grids lines every
|
|
15 degrees in latitude and longitude. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Sites</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This toggles whether a tiny square
|
|
will
|
|
be drawn at each location found in the currently loaded Sites file </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Sunlight</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This toggles whether the portion of
|
|
the
|
|
Earth's surface currently in sun light is highlighted in some
|
|
fashion. When using the Weather map or either Image projection, the
|
|
map is darkened where the Sun is currently down, and only continent
|
|
outlines are shown. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Main marker</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This toggles whether a small marker is
|
|
drawn at the location currently showing in the XEphem Main window.<br>
|
|
</div>
|
|
<br>
|
|
<b>Nightside lights</b><br>
|
|
<blockquote>This toggles whether the dark side of the view will include
|
|
lights visible from space. This option is only available using either
|
|
of the Image methods (not Graphics). Image is courtesy NASA.<br>
|
|
</blockquote>
|
|
<span style="font-weight: bold;">Live dragging</span>:<br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This toggles whether the display
|
|
graphics are updated immediately as the sliders are moved, or
|
|
whether graphics are only drawn after the sliders are released.
|
|
Also, if this option is on, moving the mouse while holding down the
|
|
middle button will cause the display to rotate about the pole when
|
|
moved left-and-right or about a horizontal line centered on the window
|
|
when moved up-and-down. If your system is sufficiently fast, the
|
|
effect in quite dramatic.<br>
|
|
<br>
|
|
</div>
|
|
<span style="font-weight: bold;">Inertial frame</span>:<br>
|
|
<br>
|
|
<div style="margin-left: 40px;">When On, the display point of view
|
|
remains fixed in space; when Off, it remains over a fixed location on
|
|
the earth's surface.<br>
|
|
<br>
|
|
</div>
|
|
<div style="margin-left: 40px;"> <a name="Earth_control_dialog"></a> </div>
|
|
<h4><a class="mozTocH1" name="mozTocId19624"></a> 4.4.3.1 Objects dialog</h4>
|
|
<div style="text-align: center;"> <img alt=""
|
|
src="png/each-control-objects.png" align="middle" height="275"
|
|
vspace="10" width="671"><br>
|
|
<br>
|
|
<div style="text-align: left;"> This dialog shows one row for each
|
|
active <a href="#Favorites">Favorite</a>. The columns are as follows:<br>
|
|
<br>
|
|
<b>Object</b><span style="font-weight: bold;"></span><br>
|
|
<div style="margin-left: 40px;">This is the name of the Object.<br>
|
|
</div>
|
|
<span style="font-weight: bold;">Show</span><br>
|
|
<div style="margin-left: 40px;"> Determines whether the object is shown
|
|
on the Earth map at all. If On, the object subearth location is
|
|
shown as a cross × surrounded by the loci of points at
|
|
which the object is 60, 30 and 0 (on the horizon) degrees
|
|
altitude. Clicking on the title toggles the individual buttons for all
|
|
objects.<br>
|
|
</div>
|
|
<span style="font-weight: bold;"></span><span style="font-weight: bold;">Label</span><br>
|
|
<div style="margin-left: 40px;"> Determines whether the name of the
|
|
object is drawn somewhat above its cross. Clicking on the title toggles
|
|
the individual buttons for all objects.
|
|
</div>
|
|
<b>Foot Print</b><span style="font-weight: bold;"></span><br>
|
|
<div style="margin-left: 40px;">The footprint is a set of three
|
|
contours
|
|
indicating the locations from which the object appears at 0, 30 and 60
|
|
degrees above the horizon. This toggle chooses whether to show these
|
|
contours or just the sub-earth postion. Clicking on the title toggles
|
|
the individual buttons for all objects.
|
|
</div>
|
|
<span style="font-weight: bold;">Orbit</span><br>
|
|
<div style="margin-left: 40px;"> Determines whether to draw the orbit
|
|
of an earth satellite. The orbit is drawn starting from the current
|
|
location of the satellite as seen from space, irrespective of
|
|
subsequent earth rotation. Clicking on the title toggles the individual
|
|
buttons for all objects.
|
|
</div>
|
|
<span style="font-weight: bold;"></span><span style="font-weight: bold;"></span><span
|
|
style="font-weight: bold;">Trail</span><br>
|
|
<div style="margin-left: 40px;"> Brings up a window to define the time
|
|
duration and labeling of the ground track of the object. See <a
|
|
href="#Trails">Trails</a> After a trail has been created, this toggle
|
|
then allows it to be turned off and on without deleting it. The
|
|
trail really is deleted if it is Off and an Update occurs. After
|
|
being deleted, this toggle again brings up the window to define
|
|
a trail. Note that the trail may be redefined as many times as
|
|
desired directly from the Trail window, it does not need to be
|
|
deleted each time. </div>
|
|
<span style="font-weight: bold;">Track</span><br>
|
|
<div style="margin-left: 40px;"> At most one button in this column may
|
|
be On. The object for which Tracking is on will remain centered
|
|
in the view each time Update occurs. </div>
|
|
<span style="font-weight: bold;">Popup ref</span><br>
|
|
<div style="margin-left: 40px;"> At most one button in this column may
|
|
be On. When right-clicking on the map with one of these buttons
|
|
on, the bearing and altitude from that location to this object
|
|
are displayed. </div>
|
|
<br>
|
|
The remaining columns are informational only but be used for <a
|
|
href="#Plot">plotted,</a> <a href="#Listing">listed</a> or used
|
|
in a <a href="#Search">solver</a> algorithm. Sub lat and long are
|
|
displayed for all types of object, the others are displayed for
|
|
Earth satellites only.<br>
|
|
<br>
|
|
<span style="font-weight: bold;">Sub lat<br>
|
|
</span><span style="font-weight: bold;">Sub long</span><br>
|
|
<div style="margin-left: 40px;"> These columns display the latitude and
|
|
longitude at which the given object appears exactly overhead. </div>
|
|
<span style="font-weight: bold;">Alt</span><br>
|
|
<div style="margin-left: 40px;"> This is the distance from the mean
|
|
geode to the satellite. </div>
|
|
<span style="font-weight: bold;">Range</span><br>
|
|
<div style="margin-left: 40px;"> This is the line of site distance from
|
|
the current Main location to the satellite. </div>
|
|
<span style="font-weight: bold;">Range'</span><br>
|
|
<div style="margin-left: 40px;"> This is the rate of change of Range.
|
|
It
|
|
is useful for computing the doppler shift of a signal arriving
|
|
from the satellite. </div>
|
|
<span style="font-weight: bold;">Sun lit</span><br>
|
|
<div style="margin-left: 40px;"> This column is a 1 or 0 depending on
|
|
whether the satellite is in sun light. Note this is <span
|
|
style="font-style: italic;">not</span> whether the subearth point is
|
|
in
|
|
sun light. </div>
|
|
<span style="font-weight: bold;">Age Days</span><br>
|
|
<div style="margin-left: 40px;"> This is the age, in days, of the
|
|
elements used
|
|
to
|
|
compute the satellite orbit. Drag is included but elements older
|
|
than a few days will already show errors. Use the handy <a
|
|
href="#WebDB">Web Update</a> button at the bottom to download the
|
|
latest elements. </div>
|
|
</div>
|
|
</div>
|
|
<a name="Mars"></a>
|
|
<h2><a class="mozTocH1" name="mozTocId624734"></a> 4.5 Mars</h2>
|
|
<img style="width: 342px; height: 382px;" alt="" title=""
|
|
src="png/mars.png" align="right" hspace="20">This
|
|
window displays an image of Mars as it currently appears from Earth
|
|
center. The orientation is
|
|
always parallel to the Martian rotation axis. The NSEW markings are
|
|
directions on the celestial sphere. <a name="Mars_mouse"></a>
|
|
<h3><a class="mozTocH1" name="mozTocId400787"></a> 4.5.1 Mars mouse</h3>
|
|
<span style="font-weight: bold;">Left Button</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> If the <span
|
|
style="font-family: monospace;">View » More Info</span>
|
|
window is open, then moving the mouse around over the image while
|
|
holding the left button will display the Martian latitude and
|
|
longitude under the cursor location. A magnifying glass also appears
|
|
attached to the cursor. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Right Button<br>
|
|
<br>
|
|
</span>
|
|
<div style="margin-left: 40px;"> Pressing the right button while over
|
|
the planet will present a popup menu. Sliding down and releasing on
|
|
the Point button in the popup will reposition the view so the
|
|
current location is centered. Repointing will also disable the shadow
|
|
and
|
|
the subearth marker until the next Update from the Main window. If
|
|
over a feature, the popup will also contain its name, type, diameter
|
|
(or largest dimension) and location. If not over a feature, just the
|
|
cursor
|
|
location is shown.<br clear="all">
|
|
<a name="Mars_control"></a> </div>
|
|
<h3><a class="mozTocH1" name="mozTocId312560"></a> 4.5.2 Mars Control menu</h3>
|
|
<span style="font-weight: bold;">Print...</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This selection allows printing the
|
|
current Mars view or saving it as a Postscript file. See <a
|
|
href="#Print">Printing</a>. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">User annotation<br>
|
|
<br>
|
|
</span>
|
|
<div style="margin-left: 40px;"> This selection brings up a window
|
|
which
|
|
allows text and lines to be drawn over the image. See <a
|
|
href="#Annotation">Annotation</a> </div>
|
|
<br>
|
|
<b>Add to movie...</b><br>
|
|
<blockquote>This selection brings up a window to allow adding the
|
|
current Mars view to a <a href="xephem.html#Movie">movie loop</a>.<br>
|
|
</blockquote>
|
|
<span style="font-weight: bold;">Close</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This selection will remove the Mars
|
|
view from the screen. If it is open it will also remove the More
|
|
Info window. </div>
|
|
<br>
|
|
<a name="Mars_view"></a>
|
|
<h3><a class="mozTocH1" name="mozTocId578544"></a> 4.5.3 Mars View menu</h3>
|
|
<span style="font-weight: bold;"><b>Half size</b><br>
|
|
</span>
|
|
<blockquote>This sets whether the map is drawn at full available
|
|
resolution or at one half resolution.<br>
|
|
</blockquote>
|
|
<span style="font-weight: bold;"></span><span style="font-weight: bold;">Flip
|
|
T/B</span><br>
|
|
<span style="font-weight: bold;">Flip L/R</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This sets whether the image is flipped
|
|
vertically or horizontally, respectively. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Grid</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This sets whether a coordinate grid is
|
|
drawn over the image. Each line is spaced at an interval of 15
|
|
degrees. Also, unless the image has been rotated, an X marks the
|
|
center of the image, that is, the subearth location.<br>
|
|
<a name="Mars_features"></a><br>
|
|
</div>
|
|
<h4><a name="mozTocId328938" class="mozTocH4"></a> 4.5.3.1 <span
|
|
style="font-weight: bold;">Features...</span></h4>
|
|
<span style="font-weight: bold;">
|
|
</span>
|
|
<div style="margin-left: 40px;"> This window displays categories of
|
|
surface features and a scrolled list of individual features sorted by
|
|
name. The features that are selected in the scrolled list are the ones
|
|
drawn on the map. Craters and single Mountains are drawn with a circle
|
|
to scale, landing sites with a small circle and other categories are
|
|
just labeled by name.<br>
|
|
<br>
|
|
Click an entry in the scrolled list to turn it on or off individually.
|
|
Or select features by category by clicking the toggle buttons down the
|
|
left and possibly <b>Toggle, All</b><b></b> and <b>None</b> as
|
|
convenient, then clicking <b>Apply</b>. <b>Ok</b> does the same but
|
|
also closes this window.<br>
|
|
<br>
|
|
As a special case if everything in the scrolled list is unselected and
|
|
one feature is selected, the map will be rotated to place the selected
|
|
feature in the center. This is handy for locating a feature by name.
|
|
Note that all features may be deselected easily by clicking <b>None</b><b></b>
|
|
then <b>Apply</b>.<br>
|
|
<br>
|
|
</div>
|
|
<div style="margin-left: 40px;"> <a name="Mars_moreinfo"></a> </div>
|
|
<h4><a class="mozTocH1" name="mozTocId984271"></a> 4.5.3.2 More info...</h4>
|
|
<div style="margin-left: 40px;"> <img
|
|
style="width: 191px; height: 293px;" alt="" title=""
|
|
src="png/mars-more-info.png" align="right" hspace="20"> The top
|
|
portion of this window reports
|
|
the location
|
|
of the cursor as it is moved over the image, if the left button is
|
|
pressed.<br>
|
|
<br>
|
|
<b>Sub Earth Lat </b>shows the Martian latitude which currently faces
|
|
the Earth. The value is computed
|
|
each time an Update is performed from the Main Menu. The scale below
|
|
allows you to set another value if desired as described below.<br>
|
|
<br>
|
|
<b>Central M Long</b> shows the central meridian longitude, or simply
|
|
Martian longitude, which currently faces the Earth. The value is
|
|
computed
|
|
each time an Update is performed from the Main Menu. The scale below
|
|
allows you to set another value if desired as described below.<br>
|
|
<br>
|
|
<b>Seeing</b> sets the size of your local atmospheric seeing disk in
|
|
arc seconds. The image will
|
|
be blurred to simulate the resolution under this condition.<br>
|
|
<br>
|
|
For browsing purposes, the scale values may be changed as desired.
|
|
Adjust
|
|
any or all scales, then press <b>Apply</b> to put the changes into
|
|
effect.
|
|
Forcing changes in this way will also temporarily disable the
|
|
shadow. At the time of the next Update, the correct current values
|
|
and the shadow will be reinstated. The Apply button is made
|
|
insensitive if the scale values are correct for the current time;
|
|
the button becomes sensitive only when the scales have been moved
|
|
manually.<br>
|
|
<br>
|
|
The values in the lower portion may be <a href="#Plot">plotted,</a> <a
|
|
href="#Listing">listed</a> or used in a <a href="#Search">solver</a>
|
|
algorithm. The values are always current when used in this way, even
|
|
if the main Mars view is closed. For faster looping, close the main
|
|
Mars display to prevent it from being redrawn each time. </div>
|
|
<br clear="all">
|
|
<a name="MarsMoons"></a>
|
|
<h4><a class="mozTocH1" name="mozTocId256891"></a> 4.5.3.3 Moon view...</h4>
|
|
<div style="margin-left: 40px;"> <img
|
|
style="width: 238px; height: 244px;" alt="" title=""
|
|
src="png/mars-moons.png" align="right" hspace="20">
|
|
This is a schematic view of Mars and its moons at the indicated date
|
|
and
|
|
time. In addition, background sky objects may also be displayed.<br>
|
|
<br>
|
|
The scale at the left controls relative magnification.<br>
|
|
<br>
|
|
The scale at the right controls the dimmest magnitude which will be
|
|
displayed. The values range from 20 at the top and 0 at the bottom.
|
|
Objects dimmer than the value specified are not shown, except that
|
|
Mars is always shown.<br>
|
|
<br>
|
|
Nominal celestial directions are indicated at the top and right edges.<br>
|
|
<br>
|
|
Moons are displayed only if they are geometrically visible. Use the
|
|
top view to see whether they are also in sun light. <a
|
|
name="MarsMoons_mouse"></a> </div>
|
|
<h5><a class="mozTocH1" name="mozTocId334996"></a> Mars Moons mouse</h5>
|
|
<div style="margin-left: 40px;"> The mouse may be used to identify any
|
|
object in the Mars view. Position the cursor near the object of
|
|
interest and select the right mouse button. A popup menu will appear
|
|
with the objects name, current location and magnitude. </div>
|
|
<br clear="all">
|
|
<a name="MarsMoons_control"></a>
|
|
<h5><a class="mozTocH1" name="mozTocId779072"></a> Mars Moons Control
|
|
menu</h5>
|
|
<span style="font-weight: bold;">Print...</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This selection allows you to print the
|
|
current view. See <a href="#Print">Print</a>. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">User annotation...</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This selection lets you place text and
|
|
lines on the current view. See <a href="#Annotation">Annotation</a>.</div>
|
|
<br>
|
|
<b>Add to movie...</b><br>
|
|
<blockquote>This selection brings up a window to allow adding the
|
|
current Martian moon view to a <a href="xephem.html#Movie">movie
|
|
loop</a>.<br>
|
|
</blockquote>
|
|
<span style="font-weight: bold;">Field Stars...</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This selection activates the Field
|
|
Star
|
|
setup window. See <a href="#FieldStars">Field stars</a>. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Telescope GoTo</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This option, when available, causes
|
|
the location of
|
|
Mars
|
|
to be sent to a telescope control process. This mechanism is
|
|
the same as that provided by the Telescope facility within the Sky
|
|
view. See <a href="#SkyView_telescope">Telescope</a> </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Movie Demo</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This option will set up the Main
|
|
window
|
|
time step controls for a 15 minute step size and start a <a
|
|
href="#main_looping">loop</a> which dramatically displays the motions
|
|
of the moons as they orbit Mars. This selection automatically disables
|
|
the <span style="font-family: monospace;">View » Sky Background</span>
|
|
selection to insure reasonable speed. Push the button again to stop
|
|
the movie. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Close</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This removes the Mars moon display,
|
|
and
|
|
the additional information window if present, from the screen. <a
|
|
name="MarsMoons_view"></a> </div>
|
|
<h5><a class="mozTocH1" name="mozTocId961374"></a> Mars Moons View menu</h5>
|
|
<span style="font-weight: bold;">Top view</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Selects whether to also display
|
|
another
|
|
window, looking down on the Mars system from above the N celestial
|
|
pole. This window will tend to remain aligned above the main view
|
|
when either is resized. Moons are displayed only if they are in sun
|
|
light. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Sky background</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Selects whether to also show objects
|
|
within the current field of view that are in the XEphem database
|
|
memory or available from the <a href="#FieldStars">Field stars</a>
|
|
facility. The size of the object is determined by the limiting
|
|
magnitude as specified by the scale at the right. Objects are drawn
|
|
using the same symbols as used by the Sky view. While this option is
|
|
on,
|
|
XEphem will continue to retrieve field stars as required. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Bright moons</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> If this option is in effect, then the
|
|
diameter of all moons will be increased by 3 pixels. This option
|
|
also insures that even those moons which are dimmer than the
|
|
limiting magnitude, as specified by the scale to the right, will be
|
|
drawn with a circle of diameter 3 pixels. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Tags<br>
|
|
<br>
|
|
</span>
|
|
<div style="margin-left: 40px;"> Whether to show the Roman numeral
|
|
designation beneath each moon and a 1 arc-minute scale calibration
|
|
line. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Flip T/B</span><br>
|
|
<span style="font-weight: bold;">Flip L/R</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> These allow the scene to be flipped
|
|
vertically and horizontally, respectively. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">More info...</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> <img alt=""
|
|
src="png/mars-moon-more-info.png" align="right" height="176"
|
|
hspace="20" width="487">This
|
|
button brings up a separate
|
|
window which
|
|
contains quantitative information about Mars's moons. All values may
|
|
be used in <a href="#Plot">plotting</a>,<a href="#Listing">listing</a>
|
|
and <a href="#Search">solving</a>.<br>
|
|
<br>
|
|
The E and S columns are 1 if the moon is geometrically visible from the
|
|
Earth and
|
|
Sun, respectively. The P column is 1 if the shadow of the moon
|
|
currently falls on the planet. The T column is 1 if the moon is
|
|
currently transiting the planet. Otherwise the columns are 0.<br>
|
|
<br>
|
|
The locations of the moons are given in two coordinate systems. The
|
|
first three columns are the displacements of the moons in Mars radii
|
|
with respect to the equatorial plane. The next two columns give the
|
|
RA and Dec location of the moons in the current epoch (as specified
|
|
on the Main window). </div>
|
|
<br clear="all">
|
|
<br>
|
|
<a name="Jupiter"></a>
|
|
<h2><a class="mozTocH1" name="mozTocId369626"></a> 4.6 Jupiter</h2>
|
|
<div style="margin-left: 40px;"> <img
|
|
style="width: 260px; height: 263px;" alt="" title=""
|
|
src="png/jupiter.png" align="right" hspace="20">
|
|
This is a view of Jupiter and its Galilean moons at the indicated date
|
|
and time. In addition, background sky objects may also be displayed.<br>
|
|
<br>
|
|
The scale at the left controls relative magnification.<br>
|
|
<br>
|
|
The scale at the right controls the dimmest magnitude which will be
|
|
displayed. Jupiter is always displayed. The values range from 20 at
|
|
the top and 0 at the bottom. Objects dimmer than the value specified
|
|
are not shown.<br>
|
|
<br>
|
|
Equatorial directions are indicated at the top and right edges.<br>
|
|
<br>
|
|
Moons are displayed only if they are geometrically visible from Earth.
|
|
Use the top view to see whether they are also in sun light.<br>
|
|
<br>
|
|
The default longitude of the GRS is set to 77 degrees, where it was
|
|
in late May of 2002. This may be changed interactively in the More
|
|
Info window. <a name="Jupiter_mouse"></a> </div>
|
|
<h3><a class="mozTocH1" name="mozTocId231060"></a> 4.6.1 Jupiter mouse</h3>
|
|
<div style="margin-left: 40px;"> The mouse may be used to identify any
|
|
object in the Jupiter view. Position the cursor near the object of
|
|
interest and select the right mouse button. A popup menu will appear
|
|
with the objects name, current location and magnitude. </div>
|
|
<br clear="all">
|
|
<br clear="all">
|
|
<a name="Jupiter_control"></a>
|
|
<h3><a class="mozTocH1" name="mozTocId192624"></a> 4.6.2 Jupiter Control menu</h3>
|
|
<span style="font-weight: bold;">Print...</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This selection allows printing the
|
|
current Jupiter view or saving it to a file. See <a href="#Print">Printing</a>.</div>
|
|
<br>
|
|
<span style="font-weight: bold;">User annotation...</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This selection brings up a window
|
|
which
|
|
allows text and lines to be drawn over the image. See <a
|
|
href="#Annotation">Annotation</a>. </div>
|
|
<br>
|
|
<b>Add to movie...</b><br>
|
|
<blockquote>This selection brings up a window to allow adding the
|
|
current Jupiter moon view to a <a href="xephem.html#Movie">movie
|
|
loop</a>.<br>
|
|
</blockquote>
|
|
<span style="font-weight: bold;">Field Stars...</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This selection activates the Field
|
|
Star
|
|
setup window. See <a href="#FieldStars">Field stars</a>. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Telescope GoTo</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This option, when available, causes
|
|
the location of
|
|
Jupiter to be sent to a telescope control process. This mechanism is
|
|
the same as that provided by the Telescope facility within the Sky
|
|
view. See <a href="#SkyView_telescope">Telescope</a> </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Movie Demo</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This option will set up the time step
|
|
controls in the Main window for a 15 minute step size and start a
|
|
loop which dramatically displays the motions of the moons as they
|
|
orbit Jupiter. This selection automatically disables the <span
|
|
style="font-family: monospace;">View » Sky Background</span>
|
|
selection to insure reasonable speed. Push the button again to stop
|
|
the movie. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Close</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This removes the Jupiter display, and
|
|
the additional information window if present, from the screen. <a
|
|
name="Jupiter_view"></a> </div>
|
|
<h3><a class="mozTocH1" name="mozTocId348716"></a> 4.6.3 Jupiter View menu</h3>
|
|
<span style="font-weight: bold;">Top view</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Selects whether to display another
|
|
window above the front view with a vantage point over the pole. This
|
|
window will try to remain aligned above the main Jupiter front view
|
|
when either is resized. Moons are displayed only if they are in sun
|
|
light. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Sky background</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Selects whether to also show objects
|
|
within the current field of view that are in the XEphem database
|
|
memory or available from the <a href="#FieldStars">Field stars</a>
|
|
facility. The size of the object is determined by the limiting
|
|
magnitude as specified by the scale at the right. Objects are drawn
|
|
using the same symbols as used by the Sky view. While this option is
|
|
on,
|
|
XEphem will continue to retrieve field stars as required. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Bright moons</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> If this option is in effect, then the
|
|
diameter of all moons will be increased by 3 pixels. This option
|
|
also insures that even those moons which are dimmer than the
|
|
limiting magnitude, as specified by the scale to the right, will be
|
|
drawn with a circle of diameter 3 pixels. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Tags</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Selects whether to show the Roman
|
|
numeral designation beneath each moon and a 1 arc-minute scale
|
|
calibration line. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Flip T/B</span><br>
|
|
<span style="font-weight: bold;">Flip L/R</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> These allow the scene to be flipped
|
|
vertically and horizontally, respectively. </div>
|
|
<h4><a class="mozTocH4" name="mozTocId944636"></a> 4.6.3.1 <span
|
|
style="font-weight: bold;">More info...</span></h4>
|
|
<div style="margin-left: 40px;"> <img alt=""
|
|
src="png/jupiter-view-more-info.png" align="right" height="264"
|
|
hspace="20" width="501">This
|
|
button brings up a separate window which contains quantitative
|
|
information about Jupiter's moons and central meridian longitude.
|
|
All values may be used in <a href="#Plot">plotting</a>,<a
|
|
href="#Listing">listing</a> and <a href="#Search">solving</a>.<br>
|
|
<br>
|
|
The E and S columns are 1 if the moon is geometrically visible from the
|
|
Earth and
|
|
Sun, respectively. The P column is 1 if the shadow of the moon
|
|
currently falls on the planet. The T column is 1 if the moon is
|
|
currently transiting the planet. Otherwise the columns are 0.<br>
|
|
<br>
|
|
The locations of the moons are given in two coordinate systems. The
|
|
first three columns are the displacements of the moons in Jupiter
|
|
radii with respect to the celestial plane. The next two columns give
|
|
the RA and Dec location of the moons in the current equinox (as
|
|
specified on the Main window).<br>
|
|
<br>
|
|
Value of the System II longitude of the Great Red Spot is displayed.
|
|
The value may be changed according to current information. Pressing
|
|
Enter will update the Jupiter display with the new value. </div>
|
|
<br clear="all">
|
|
<br>
|
|
<br>
|
|
<a name="Saturn"></a>
|
|
<h2><a class="mozTocH1" name="mozTocId962916"></a> 4.7 Saturn</h2>
|
|
<div style="margin-left: 40px;"> <img
|
|
style="width: 220px; height: 227px;" alt="" title=""
|
|
src="png/saturn.png" align="right" hspace="20">
|
|
This is a schematic view of Saturn, its rings and moons at the
|
|
indicated
|
|
date and time. In addition, background sky objects may also be
|
|
displayed.<br>
|
|
<br>
|
|
The scale at the left controls relative magnification.<br>
|
|
<br>
|
|
The scale at the right controls the dimmest magnitude which will be
|
|
displayed. Saturn and its rings are always displayed. The values
|
|
range from 20 at the top and 0 at the bottom. Objects dimmer than
|
|
the value specified are not shown.<br>
|
|
<br>
|
|
Nominal celestial directions are indicated at the top and right edges.<br>
|
|
<br>
|
|
Moons are displayed only if they are geometrically visible. Use the
|
|
top view to see whether they are also in sun light. <a
|
|
name="Saturn_mouse"></a> </div>
|
|
<h3><a class="mozTocH1" name="mozTocId493832"></a> 4.7.1 Saturn mouse</h3>
|
|
<div style="margin-left: 40px;"> The mouse may be used to identify any
|
|
object in the Saturn view. Position the cursor near the object of
|
|
interest and select the right mouse button. A popup menu will appear
|
|
with the objects name, current location and magnitude.<br clear="all">
|
|
<a name="Saturn_control"></a> </div>
|
|
<h3><a class="mozTocH1" name="mozTocId379478"></a> 4.7.2 Saturn Control menu</h3>
|
|
<span style="font-weight: bold;">Print...</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This selection allows printing the
|
|
current Saturn view or saving it to a file. See <a href="#Print">Printing</a>.</div>
|
|
<br>
|
|
<span style="font-weight: bold;">User annotation...</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This selection brings up a window
|
|
which
|
|
allows text and lines to be drawn over the image. See <a
|
|
href="#Annotation">Annotation</a>. </div>
|
|
<br>
|
|
<b>Add to movie...</b><br>
|
|
<blockquote>This selection brings up a window to allow adding the
|
|
current Saturn moon view to a <a href="xephem.html#Movie">movie loop</a>.<br>
|
|
</blockquote>
|
|
<span style="font-weight: bold;">Field Stars...</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This selection activates the Field
|
|
Star
|
|
setup window. See <a href="#FieldStars">Field stars</a>. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Telescope GoTo</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This option, when available, causes
|
|
the location of
|
|
Saturn to be sent to a telescope control process. This mechanism is
|
|
the same as that provided by the Telescope facility within the Sky
|
|
view. See <a href="#SkyView_telescope">Telescope</a> </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Movie Demo</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This option will set up the time step
|
|
controls in the Main window for a 15 minute step size and start a <a
|
|
href="#main_looping">loop</a> which dramatically displays the motions
|
|
of the moons as they orbit Saturn. This selection automatically
|
|
disables
|
|
the <span style="font-family: monospace;">View » Sky Background</span>
|
|
selection to insure reasonable speed. Push the button again to stop
|
|
the movie. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Close</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This removes the Saturn display, and
|
|
the additional information window if present, from the screen. </div>
|
|
<br>
|
|
<a name="Saturn_view"></a>
|
|
<h3><a class="mozTocH1" name="mozTocId87642"></a> 4.7.3 Saturn View menu</h3>
|
|
<span style="font-weight: bold;">Top view</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Selects whether to also display
|
|
another
|
|
window, looking down on the Saturnian system from above the
|
|
celestial N pole. This window will tend to remain aligned above the
|
|
main front view when either is resized. Moons are displayed only if
|
|
they are in sun light. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Sky background</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Selects whether to also show objects
|
|
within the current field of view that are in the XEphem database
|
|
memory or available from the <a href="#FieldStars">Field stars</a>
|
|
facility. The size of the object is determined by the limiting
|
|
magnitude as specified by the scale at the right. Objects are drawn
|
|
using the same symbols as used by the Sky view. While this option is
|
|
on,
|
|
XEphem will continue to retrieve field stars as required. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Bright moons</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> If this option is in effect, then the
|
|
diameter of all moons will be increased by 3 pixels. This option
|
|
also insures that even those moons which are dimmer than the
|
|
limiting magnitude, as specified by the scale to the right, will be
|
|
drawn with a circle of diameter 3 pixels. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Tags</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Selects whether to show the Roman
|
|
numeral designation beneath each moon and a 1 arc-minute scale
|
|
calibration line. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Flip T/B</span><br>
|
|
<span style="font-weight: bold;">Flip L/R</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> These allow the scene to be flipped
|
|
vertically and horizontally, respectively. </div>
|
|
<h4><a class="mozTocH4" name="mozTocId949756"></a> 4.7.3.1 <span
|
|
style="font-weight: bold;">More info...</span></h4>
|
|
<div style="margin-left: 40px;"> <img alt=""
|
|
src="png/saturn-more-info.png" align="right" height="308" hspace="10"
|
|
width="513">This button
|
|
brings up a separate window
|
|
which
|
|
contains quantitative information about Saturn's moons and its
|
|
rings. All values may be used in <a href="#Plot">plotting</a>,<a
|
|
href="#Listing">listing</a> and <a href="#Search">solving</a>. </div>
|
|
<div style="margin-left: 40px;"> <br>
|
|
The E and S columns are 1 if the moon is geometrically visible from the
|
|
Earth and
|
|
Sun, respectively. The P column is 1 if the shadow of the moon
|
|
currently falls on the planet. The T column is 1 if the moon is
|
|
currently transiting the planet. Otherwise the columns are 0.<br>
|
|
<br>
|
|
The ring tilt is displayed as the angle above or below the line of
|
|
sight to Saturn from the Sun and the Earth. A positive value means
|
|
the front of the rings are tilted southward.<br>
|
|
<br>
|
|
The locations of the moons are given in two coordinate systems. The
|
|
first three columns are the displacements of the moons in Saturn
|
|
radii with respect to the celestial plane. The next two columns give
|
|
the RA and Dec location of the moons in the current equinox (as
|
|
specified on the Main window). </div>
|
|
<br clear="all">
|
|
<a name="Uranus"></a>
|
|
<h2><a class="mozTocH1" name="mozTocId621414"></a> 4.8 Uranus</h2>
|
|
<div style="margin-left: 40px;"> <img
|
|
style="width: 294px; height: 277px;" alt="" title=""
|
|
src="png/uranus.png" align="right" hspace="20">
|
|
This is a schematic view of Uranus and its moons at the indicated date
|
|
and time. In addition, background sky objects may also be displayed.<br>
|
|
<br>
|
|
The scale at the left controls relative magnification.<br>
|
|
<br>
|
|
The scale at the right controls the dimmest magnitude which will be
|
|
displayed. Uranus is always displayed. The values range from 20 at
|
|
the top and 0 at the bottom. Objects dimmer than the value specified
|
|
are not shown.<br>
|
|
<br>
|
|
Nominal celestial directions are indicated at the top and right edges.<br>
|
|
<br>
|
|
Moons are displayed only if they are geometrically visible. Use the
|
|
top view to see whether they are also in sun light. <a
|
|
name="Uranus_mouse"></a> </div>
|
|
<h3><a class="mozTocH1" name="mozTocId644069"></a> 4.8.1 Uranus mouse</h3>
|
|
<div style="margin-left: 40px;"> The mouse may be used to identify any
|
|
object in the Uranus view. Position the cursor near the object of
|
|
interest and select the right mouse button. A popup menu will appear
|
|
with the objects name, current location and magnitude.<br clear="all">
|
|
<a name="Uranus_control"></a> </div>
|
|
<h3><a class="mozTocH1" name="mozTocId665534"></a> 4.8.2 Uranus Control menu</h3>
|
|
<span style="font-weight: bold;">Print...</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This selection allows printing the
|
|
current Uranus view or saving it to a file. See <a href="#Print">Print</a>.</div>
|
|
<br>
|
|
<span style="font-weight: bold;">User annotation...</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This selection brings up a window
|
|
which
|
|
allows text and lines to be drawn over the image. See <a
|
|
href="#Annotation">Annotation</a>. </div>
|
|
<br>
|
|
<b>Add to movie...</b><br>
|
|
<blockquote>This selection brings up a window to allow adding the
|
|
current Uranus moon view to a <a href="xephem.html#Movie">movie loop</a>.<br>
|
|
</blockquote>
|
|
<span style="font-weight: bold;">Field Stars...</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This selection activates the Field
|
|
Star
|
|
setup window. See <a href="#FieldStars">Field stars</a>. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Telescope GoTo</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This option, when available, causes
|
|
the location of
|
|
Uranus to be sent to a telescope control process. This mechanism is
|
|
the same as that provided by the Telescope facility within the Sky
|
|
view. See <a href="#SkyView_telescope">Telescope</a> </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Movie Demo</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This option will set up the time step
|
|
controls in the Main window for a 15 minute step size and start a <a
|
|
href="#main_looping">loop</a> which dramatically displays the motions
|
|
of the moons as they orbit Uranus. This selection automatically
|
|
disables
|
|
the <span style="font-family: monospace;">View » Sky Background</span>
|
|
selection to insure reasonable speed. Push the button again to stop
|
|
the movie. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Close</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This removes the Saturn display, and
|
|
the additional information window if present, from the screen. </div>
|
|
<a name="Uranus_view"></a>
|
|
<h3><a class="mozTocH1" name="mozTocId109743"></a> 4.8.3 Uranus View menu</h3>
|
|
<span style="font-weight: bold;">Top view</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Selects whether to also display
|
|
another
|
|
window, looking down on the Uranus system from above the N celestial
|
|
pole. This window will tend to remain aligned above the main view
|
|
when either is resized. Moons are displayed only if they are in sun
|
|
light. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Sky background</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Selects whether to also show objects
|
|
within the current field of view that are in the XEphem database
|
|
memory or available from the <a href="#FieldStars">Field stars</a>
|
|
facility. The size of the object is determined by the limiting
|
|
magnitude as specified by the scale at the right. Objects are drawn
|
|
using the same symbols as used by the Sky view. While this option is
|
|
on,
|
|
XEphem will continue to retrieve field stars as required. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Bright moons</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> If this option is in effect, then the
|
|
diameter of all moons will be increased by 3 pixels. This option
|
|
also insures that even those moons which are dimmer than the
|
|
limiting magnitude, as specified by the scale to the right, will be
|
|
drawn with a circle of diameter 3 pixels. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Tags</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Selects whether to show the Roman
|
|
numeral designation beneath each moon and a 1 arc-minute scale
|
|
calibration line. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Flip T/B</span><br>
|
|
<span style="font-weight: bold;">Flip L/R</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> These allow the scene to be flipped
|
|
vertically and horizontally, respectively. </div>
|
|
<h4><a class="mozTocH4" name="mozTocId186995"></a> 4.8.3.1 <span
|
|
style="font-weight: bold;">More info...</span></h4>
|
|
<div style="margin-left: 40px;"> <img alt=""
|
|
src="png/uranus-more-info.png" align="right" height="224" hspace="20"
|
|
width="495">This button
|
|
brings up a separate window
|
|
which
|
|
contains quantitative information about Uranus's moons. All values
|
|
may be used in <a href="#Plot">plotting</a>, <a href="#Listing">listing</a>
|
|
and <a href="#Search">solving.</a><br>
|
|
<br>
|
|
The E and S columns are 1 if the moon is geometrically visible from the
|
|
Earth and
|
|
Sun, respectively. The P column is 1 if the shadow of the moon
|
|
currently falls on the planet. The T column is 1 if the moon is
|
|
currently transiting the planet. Otherwise the columns are 0.<br>
|
|
<br>
|
|
The locations of the moons are given in two coordinate systems. The
|
|
first three columns are the displacements of the moons in Uranus
|
|
radii with respect to the celestial plane. The next two columns give
|
|
the RA and Dec location of the moons in the current equinox (as
|
|
specified on the Main window). </div>
|
|
<br clear="all">
|
|
<br>
|
|
<h2><a class="mozTocH1" name="mozTocId640289"></a> 4.9 Solar System</h2>
|
|
<img alt="" src="png/solsys.png" align="right" height="283" hspace="10"
|
|
vspace="10" width="430">This is a graphical representation of the
|
|
solar system. The Sun is
|
|
always at the center of the screen, marked with a small circle. The
|
|
set of objects displayed are the ones from the <a
|
|
href="xephem.html#Favorites">Favorites</a>
|
|
list that are solar system objects. Objects with defined date ranges
|
|
are only shown at valid times.<br>
|
|
<a name="Solsys_scales"></a>
|
|
<h3><a class="mozTocH1" name="mozTocId474567"></a> 4.9.1 Solar System Scales</h3>
|
|
The three scales at the edges control the position of the observer.<br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> The vertical scale on the <span
|
|
style="font-weight: bold;">left</span> controls the distance from the
|
|
Sun. You are closer as the scale is slid further up. You can also
|
|
control this with the keypad + and - keys. Using the key alone moves
|
|
by 2% little, with Shift moves by 10%. </div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> The horizontal scale across the <span
|
|
style="font-weight: bold;">bottom</span> of the view controls the
|
|
heliocentric longitude. Think of it as a rotation about the central
|
|
axis. The value of the scale is the heliocentric longitude vector
|
|
pointing straight at you. You can also control this with the keypad
|
|
Left and Right arrow keys. Using the key alone moves by 2%, with
|
|
Shift moves 10%. </div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> The vertical scale on the <span
|
|
style="font-weight: bold;">right</span> controls the heliocentric
|
|
latitude, your angle above or below the ecliptic plane. You can also
|
|
control this with the keypad Up and Down arrow keys. Using the key
|
|
alone moves by 2%, with Shift moves 10%. </div>
|
|
<br>
|
|
Changes to the scales take effect as you drag, unless the <span
|
|
style="font-family: monospace;">View » All Objects</span>
|
|
option is on in which case the change does not take effect until you
|
|
release the scale. <a name="Solsys_mouse"></a>
|
|
<h3><a class="mozTocH1" name="mozTocId533766"></a> 4.9.2 Solar System mouse</h3>
|
|
<span style="font-weight: bold;">Right button</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Clicking the right mouse button near
|
|
an
|
|
object will pop up a menu with additional information. RA and Dec
|
|
are displayed as of the time the dot was computed. The RA, Dec and
|
|
Mag given for the Earth is that of the Sun. </div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> <span style="font-weight: bold;">Persistent
|
|
Label</span> toggles whether the label for the object is displayed
|
|
regardless of whether the <span style="font-family: monospace;">View
|
|
» Labels</span> option is activated.<br>
|
|
<br>
|
|
<a name="Solsys_control"></a> </div>
|
|
<h3><a class="mozTocH1" name="mozTocId864834"></a> 4.9.3 Solar System Control
|
|
menu</h3>
|
|
<span style="font-weight: bold;">Print...</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This selection allows printing the
|
|
current Solar System view or saving it to a file. See <a
|
|
href="xephem.html#Print">Printing</a>.
|
|
</div>
|
|
<br>
|
|
<span style="font-weight: bold;">Favorites...</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> The Solar System view displays the
|
|
current set of <a href="xephem.html#Favorites">Favorites</a> that
|
|
are in the
|
|
solar
|
|
system. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">User annotation...</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This selection brings up a window
|
|
which
|
|
allows text and lines to be drawn over the image. See <a
|
|
href="xephem.html#User_annotation_">Annotation</a> </div>
|
|
<br>
|
|
<b>Add to movie...</b><br>
|
|
<blockquote>This selection brings up a window to allow adding the
|
|
current Solar System view to a <a href="xephem.html#Movie">movie
|
|
loop</a>.<br>
|
|
</blockquote>
|
|
<span style="font-weight: bold;">Create Trails...</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This button will bring up a window to
|
|
set up making a trail for each object as they travel from their
|
|
current positions. Each trail time is drawn connected together with
|
|
a solid line with each point indicated with a small dot. The time
|
|
stamps shown with the trails, if any, are always in UTC. For the
|
|
trail to be visible, the Trails option must be activated. Only one
|
|
set of trails is supported at a time. Creating new trails will
|
|
delete the old ones. The trails will also be discarded if a user
|
|
defined
|
|
object is changed or an Update occurs from the Main window. Only the
|
|
Favorites are trailed. The other solar system objects, if any, are
|
|
always shown in their current positions. See <a
|
|
href="xephem.html#Trails">Trails</a>.</div>
|
|
<br>
|
|
<span style="font-weight: bold;">Movie Demo<br>
|
|
<br>
|
|
</span>
|
|
<div style="margin-left: 40px;"> This push button will set the Main
|
|
window Step to 5 days and start <a href="xephem.html#main_looping">looping</a>
|
|
with a very large number of steps. Press the button again or use
|
|
Stop control in the Main window to stop the movie. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Live Dragging</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This toggle button selects whether the
|
|
graphics are redrawn in real time as the various scale controls are
|
|
being slid, or whether the graphics are not redrawn until the mouse
|
|
is released. The response depends on the speed of the computer, display
|
|
and data bandwidth. If the system is fast enough, turning this on
|
|
can produce dramatic depth clues for complex solar system views;
|
|
also try it in Stereo. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Stereo pair</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This toggle button is used to bring up
|
|
another image of the solar system from a slightly displaced vantage
|
|
point. Adjusting your gaze to fuse the two images together will
|
|
reveal a 3D image. This effect is most pronounced if fairly lengthy
|
|
trails are created, legs are turned on and the Ecliptic plane circles
|
|
are turned off. This effect was designed
|
|
primarily to help visualize the orbits of comets. </div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> At the bottom of the stereo display is
|
|
a scale to control the amount of parallax to introduce. The parallax
|
|
is only introduced in the plane of the ecliptic. This works well for
|
|
low latitudes but when viewing from near the poles it just moves
|
|
everything equally.<br>
|
|
<br>
|
|
If you prefer focusing your eyes in front of the screen, move the
|
|
parallax control somewhat to the left; if you prefer to relax your
|
|
eyes and focus at infinity then move the parallax control to the
|
|
right. You can also control this scale with the keypad slash (/) and
|
|
star (*) keys. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Close</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This push button will close both the
|
|
main Solar system view and the Stereo view. If the Solar System view
|
|
is closed while the Stereo window is on, it will reappear when the
|
|
Solar System window is reactivated. <a name="Solsys_view"></a> </div>
|
|
<h3><a class="mozTocH1" name="mozTocId885716"></a> 4.9.4 Solar System View
|
|
menu</h3>
|
|
<span style="font-weight: bold;">Trails</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This toggles whether trails, if
|
|
currently defined, are displayed. The trails may be turned on and
|
|
off as desired without loss but the trails are permanently discarded
|
|
when the next Update from the Main window occurs. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Ecliptic</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This toggle button controls the
|
|
display
|
|
of a set of circles in the ecliptic plane, spaced at regular
|
|
intervals. The interval between each circle is displayed at the
|
|
upper left of the view. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Labels</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This option causes each object's name
|
|
to appear. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Legs</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This toggle button controls whether a
|
|
line is drawn from each object down to the ecliptic. This aids in
|
|
visualizing the 3D location of the objects. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">DB too</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This allows showing all objects
|
|
currently loaded into memory that lie within the solar system, in
|
|
addition to the Favorites. </div>
|
|
<br>
|
|
<a name="SkyView"></a>
|
|
<h1><a class="mozTocH1" name="mozTocId792513"></a> 5.0 Sky View</h1>
|
|
<img style="width: 497px; height: 498px;" alt="" title=""
|
|
src="png/sky-view.png" align="right" hspace="20"> This view presents a
|
|
schematic representation of the sky showing database
|
|
objects and useful auxiliary information. A FITS file image can also
|
|
be displayed simultaneously.<br>
|
|
<br>
|
|
The dominant center area displays each object that meets the brightness
|
|
and type filter selection criteria. Objects with defined date ranges
|
|
are
|
|
only shown at valid times. A menu bar across the top offers access to
|
|
all functions. Fast access to certain functions are available from the
|
|
surrounding toolbars. The mouse buttons can be used inside the display
|
|
area for additional functionality specific to the exact location of
|
|
the cursor when clicked.<br>
|
|
<br>
|
|
Note that while <a href="#main_looping">looping</a> with Pause set to
|
|
0 the Sky View is not updated (although all quantitative information
|
|
is always updated internally each step). This is to permit creating
|
|
plots and using other XEphem features that use many time increments to
|
|
run much more quickly if the Sky View is unmanaged or with Pause set
|
|
to 0.<br>
|
|
<br>
|
|
If the object is an Earth satellite, its label will be surrounded in
|
|
parentheses if it eclipsed at that location.
|
|
<br clear="all">
|
|
<a name="SkyView_mouse"></a>
|
|
<h2><a class="mozTocH1" name="mozTocId692938"></a> 5.1 Sky View mouse</h2>
|
|
The mouse serves many purposes in the Sky View. Exactly what it does
|
|
at any one time depends on whether it is located over an object and on
|
|
the states of some of the toolbar buttons.<br>
|
|
<br>
|
|
<span style="font-weight: bold;">No buttons:</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> <span style="font-weight: bold;"><img
|
|
alt="" src="png/sky-upperleft-roaming.png" align="left" height="60"
|
|
hspace="20" width="177"></span><img style="width: 101px; height: 57px;"
|
|
alt="" title="" src="png/sky-upperright-roaming.png" align="right"
|
|
hspace="20">Generally
|
|
nothing happens when the mouse is over the Sky View and no buttons
|
|
are being pressed. However, if the Corner Coordinates toolbar button
|
|
(upper right) is On, basic data describing the position of the
|
|
cursor are displayed in the upper corners whenever the cursor is
|
|
over the Sky even when no buttons are depressed. These data include: </div>
|
|
<br clear="all">
|
|
<ul>
|
|
<li><span style="font-weight: bold;">In the Upper left corner:</span><br>
|
|
</li>
|
|
</ul>
|
|
<ul style="margin-left: 40px;">
|
|
<li>RA, Dec and Hour angle equatorial coordinates;</li>
|
|
<li>the great-circle distance and bearing between the current
|
|
position and the
|
|
point at which the left button was last clicked;</li>
|
|
<li>constellation name;</li>
|
|
<li>if displaying FITS image, raw image pixel coordinates. <span
|
|
style="font-style: italic;">N.B. FITS coords = XEphem coords + 1</span><br
|
|
clear="all">
|
|
</li>
|
|
</ul>
|
|
<ul style="font-weight: bold;">
|
|
<li>In the Upper right corner:</li>
|
|
</ul>
|
|
<ul style="margin-left: 40px;">
|
|
<li>Alt, Az and Zenith horizon coordinates;</li>
|
|
<li>Galactic latitude and longitude<br clear="all">
|
|
<li>Parallactic angle, +/-180 +west<br clear="all">
|
|
</li>
|
|
</ul>
|
|
<div style="margin-left: 40px;"> The coordinates are derived directly
|
|
from the screen location and know nothing of the displayed objects.
|
|
Thus, they neglect parallax (i.e., assume everything is at infinity).<br>
|
|
<br>
|
|
If the Telescope Marker is active and a telescope control process
|
|
is reporting telescope position information, then when the cursor is
|
|
outside the Sky View the data in the corners refer to the telescope
|
|
marker position, not the cursor position. This information is not
|
|
displayed if any keyboard keys or mouse buttons are pressed. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Left button:</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> <img
|
|
style="width: 99px; height: 57px;" alt="" title=""
|
|
src="png/sky-upperright-delta-roaming.png" align="right" hspace="20"><img
|
|
alt="" src="png/sky-upperleft-delta-roaming.png" align="left"
|
|
height="64" hspace="20" width="177">If
|
|
the
|
|
Region of Interest toolbar button is On and the left mouse button is
|
|
pressed, then the information in the upper left and right corners
|
|
changes into delta information, that is, the changes in the various
|
|
coordinates with respect to the position where the left button was
|
|
last pressed. </div>
|
|
<br clear="all">
|
|
<br>
|
|
<div style="margin-left: 40px;"> If the ROI toolbar button is On,
|
|
pressing and dragging the left mouse button draws a Region of
|
|
Interest box. This ROI can serve two roles. One is a way to zoom.
|
|
With the ROI toolbar button On, click in the Sky View with the left
|
|
mouse button and begin to draw a box surrounding a region of
|
|
interest. When the button is released, the ROI becomes fixed into
|
|
position. To perform the zoom, press Zoom In in the tool bar. The
|
|
current size, position, and ROI are saved and the Sky View is
|
|
changed to expand the new area. The Zoom Back tool bar button then
|
|
becomes available to restore the display to its previous size and
|
|
position. The Zoom In and Zoom Back buttons work as a pair for
|
|
arbitrary
|
|
levels of undo and redo. This Zooming is implemented by actually
|
|
sliding the scales around the edges of the Sky View just as if you
|
|
had done it manually. Thus, the selected area may be rotated after
|
|
the zoom due to a change in perspective in the map projection. This
|
|
is a feature. </div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> The other use for the ROI is available
|
|
only when an image is being display. Basic statistics are computed
|
|
for the pixels that lie within the ROI box. Also only while an image
|
|
is displayed, the left mouse button may be used to position a
|
|
Magnifying
|
|
glass; graph the pixels along an arbitrary cross sectional slice
|
|
through
|
|
the image; and compute and display high quality photometric and
|
|
astrometric information about the star nearest the cursor based on 2D
|
|
Gaussian fitting. See <a href="#SkyIP">Image analysis</a>. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Middle button:</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> While the middle button is depressed,
|
|
the cursor is changed to a fleur pattern. Moving the mouse left and
|
|
right is like moving the scale at the bottom; moving it up and down
|
|
is like moving the scale at the right. This provides a simple method
|
|
to pan the display. This feature is not yet available while
|
|
displaying an image. If the <span style="font-weight: bold;">Live
|
|
dragging</span> option is turned on (see <span
|
|
style="font-family: monospace;">Control » Options</span>), the
|
|
panning occurs immediately. If this is painfully slow on your system
|
|
then turn this off so the screen is only redrawn one time when the
|
|
button is released. </div>
|
|
<br>
|
|
<span style="font-weight: bold;"><a name="Sky_view_popup_right_button"></a>Right
|
|
button:</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> <img alt=""
|
|
src="png/sky-popup-menu.png" align="right" height="297" hspace="20"
|
|
width="146">If
|
|
the right button is clicked over the
|
|
Sky View,
|
|
then a popup menu will appear. If the button is clicked and
|
|
released, the menu will stay up and can be used like any other menu.
|
|
Or the button may be pressed and held while you slide the cursor to
|
|
the desired button and let go. Try both and use whichever procedure you
|
|
prefer. </div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> The popup contains information and
|
|
controls germane to the exact position of the cursor when the button
|
|
was clicked. The entries in the popup menu vary depending on whether
|
|
the cursor was near an object or over empty sky. If the cursor is
|
|
near a object, data is shown which are exactly the same as that
|
|
which is available in the <a href="#Data_Table">Data Table</a> window.
|
|
If a trailed object is selected, the data applies at the
|
|
time for that position. If the cursor was not near an object, basic
|
|
information based on the location of the cursor itself is shown. </div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> The popup also offers several control
|
|
operations, as follows. Remember, only the ones relevant to the
|
|
current situation and toolbar choices will appear.<br>
|
|
<br>
|
|
</div>
|
|
<ul>
|
|
<li><b>Name</b> will show the name of the object. If alternate names
|
|
are available they will be displayed in a pullright cascade menu.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><b>Type</b> will display a brief description of the type of
|
|
object.<br>
|
|
</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Center</span> will change the
|
|
Sky View pointing direction to place the given object (or location)
|
|
at the center of the field of view.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Center + Zoom</span> <span
|
|
style="font-weight: bold;">» </span>is like
|
|
Center but will also zoom in or out the amount selected in the
|
|
pullright cascade menu.<br>
|
|
<br>
|
|
</li>
|
|
<li><span style="font-weight: bold;">Persistent Label » on
|
|
Left on Right</span> will toggle whether a label is drawn on the left
|
|
or right side of the current object. The label will consist of the
|
|
name and/or the magnitude, depending on which options are selected
|
|
in the <span style="font-family: monospace;">SkyView » Options</span>
|
|
Labeling section. If neither are selected, the label will consist of
|
|
the name. Persistent labels are always on, that is, they are not
|
|
subject to magnitude limits, options, or object type filtering. Note
|
|
this option is maintained separately for trailed objects and for the
|
|
untrailed objects; that is, you have independent control over
|
|
labeling for a trailed object and its currently displayed object
|
|
since the latter also always appears in the trailed list. This can
|
|
be somewhat confusing for trails which begin Now since, in effect,
|
|
the first item is drawn twice (once just because it is an object
|
|
like any other, and again as a member of the set of trail history
|
|
points).</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Place eyepiece</span> will cause
|
|
an eyepiece symbol to be drawn centered under the mouse location. The
|
|
eyepiece shape and size are defined in the Eyepiece Setup window,
|
|
available at <span style="font-family: monospace;">Control »
|
|
Eyepieces</span>. Both the RA-Dec and Alt-Az of the location are
|
|
saved and the one matching the Display mode is used when the
|
|
eyepiece is drawn on the Sky View. In this way eyepieces can be
|
|
fixed in either coordinate system. See <a href="#SkyView_eyepieces">Eyepieces</a>.<br>
|
|
<br>
|
|
</li>
|
|
<li><span style="font-weight: bold;">Delete eyepiece</span> will
|
|
delete the closest eyepiece covering this mouse location. The search
|
|
algorithm uses the smaller of the two dimensions of the eyepiece so
|
|
it may be necessary to get close to the center depending on the shape.<br>
|
|
<br>
|
|
</li>
|
|
<li><span style="font-weight: bold;">Telescope GoTo</span> will cause
|
|
the coordinates of the cursor to be sent to the INDI telescope control
|
|
process. The command is not issued if the coordinates are below the
|
|
horizon. This button is only present if the connected process is
|
|
running. See <a href="#SkyView_telescope">Telescope.</a></li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Add to logbook</span> will copy
|
|
pertinent position and descriptive information about the current object
|
|
to a new entry in the <a href="#obslog">Observers logbook</a>. This
|
|
selection only appears if the logbook tool window is currently open.<br>
|
|
</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">New Photom ref</span> only
|
|
appears if an image is being displayed, the 2D Gaussian image analysis
|
|
tool is up, and the cursor was clicked near a database object. If all
|
|
this is so, then said object is used as the new reference for
|
|
photometric comparisons, and the magnitude of the object from the
|
|
database is set as the reference for subsequent use.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Show orbit...</span> is only
|
|
present
|
|
if the selected object is a Binary system. It brings up a window
|
|
showing
|
|
the
|
|
orbit of the secondary around the primary and an ephemeris for one
|
|
revolution. See <a href="#SkyView_binary">Binary Star Map</a> for more
|
|
information.<br>
|
|
</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Add to Favorites</span> will add
|
|
this object to the <a href="#Favorites">Favorites</a> list. </li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Create Trail</span><b>...</b>
|
|
will bring up a window from which a trail may be easily defined,
|
|
computed and displayed. The button is labeled <span
|
|
style="font-weight: bold;">Change Trail</span> if the selected
|
|
object already has a defined trail. Only one trail per object is
|
|
supported. See <a href="#Trails">Trails.</a></li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Track</span> will toggle object
|
|
tracking for this object. If a trail object is chosen, the tracking
|
|
will apply to the current position of the object. See the discussion
|
|
for the <span style="font-family: monospace;">Control » Tracking</span>
|
|
toggle button for more details.</li>
|
|
</ul>
|
|
<ul>
|
|
<li><span style="font-weight: bold;">Trail</span> is only present
|
|
if the selected object has a trail defined. If it has a trail, the
|
|
toggle state indicates whether the trail is being displayed. Note
|
|
that turning off a trail does not actually discard the trail until
|
|
the next Update occurs from the Main window.</li>
|
|
</ul>
|
|
<b><span style="font-weight: bold;"></span></b>
|
|
<b><a name="SkyView_toolbars"></a></b>
|
|
<h2><a class="mozTocH3" name="mozTocId542032"></a> 5.2 <b><a class="mozTocH1"
|
|
name="mozTocId103927"></a> </b>Toolbars</h2>
|
|
<table style="text-align: left; width: 100%;" summary="skyview toolbars"
|
|
border="1" cellpadding="2" cellspacing="2">
|
|
<tbody>
|
|
<tr>
|
|
<td colspan="1" rowspan="2"
|
|
style="vertical-align: top; text-align: left; width: 150px;"><img
|
|
style="width: 141px; height: 324px;" alt="" title=""
|
|
src="png/sky-view-how-tb.png"><br>
|
|
</td>
|
|
<td style="vertical-align: top; height: 160px;" align="center"><img
|
|
alt="" src="png/sky-view-what-tb.png" height="180" width="456"><br>
|
|
</td>
|
|
<td colspan="1" rowspan="2"
|
|
style="vertical-align: top; width: 180px; text-align: right;"><img
|
|
style="width: 125px; height: 287px;" alt="" title=""
|
|
src="png/sky-view-where-tb.png"><br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top;">The toolbars are divided into
|
|
three broad categories. Down the left are choices that effect How the
|
|
scene is portrayed, such as coordinate system, flipping and
|
|
magnitude limits. Across the top the choices effect What is
|
|
displayed, such as coordinate grids, local horizon, and the
|
|
classes of celestial objects. All of the buttons in the Left and
|
|
Top toolbars are just convenient shortcuts to functions that can
|
|
also be accessed from the Options and Filter windows available
|
|
in the Sky View Control menu.<br>
|
|
<br>
|
|
The toolbar down the right side is a little different. These
|
|
buttons share a broad common theme of Where objects or
|
|
information are located. Some also effect how the mouse operates.</td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
<br>
|
|
<a name="SkyView_scales"></a>
|
|
<h2><a class="mozTocH1" name="mozTocId217563"></a> 5.3 Scale controls</h2>
|
|
<span style="font-weight: bold;">FOV<br>
|
|
<br>
|
|
</span>
|
|
<div style="margin-left: 40px;"> The vertical scale on the left side
|
|
sets the vertical field of view of the display. The horizontal field
|
|
of view is determined by the width of the window at the same scale.
|
|
The FOV can be varied in 5 minute increments from 0:05 through 180
|
|
degrees. The buttons below offer a quick way to set the scale to
|
|
exactly
|
|
90 degrees and to resize the window (by changing the width) to 1:1
|
|
and 2:1 Width:Height aspect ratios. When an image is loaded, an
|
|
additional button appears labeled Image. Clicking this will resize the
|
|
window to match the aspect ratio of the image. The FOV scale may also
|
|
be changed
|
|
using the keypad + and - keys. Using the key alone moves by 2%, with
|
|
Shift moves 10%. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Alt / Dec</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> The vertical scale on the right side
|
|
sets either the center altitude or declination, depending on the
|
|
display mode. The value can be varied from -90 to +90 in increments
|
|
of 5 minutes. The buttons below presents a quick way to center the
|
|
scale at exactly 45, 0 or -45 degrees. The Alt/Dec scale may also be
|
|
changed using the keypad Up and Down arrow keys (make sure your NumLock
|
|
is off). Using the key alone moves by 2%, with Shift moves 10%. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Az / RA</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> The horizontal scale across the bottom
|
|
sets either the center azimuth or RA, depending on the display mode.
|
|
In Alt-Az mode this sets azimuth and can be varied from 0 to 359:55
|
|
degrees in steps of 5 minutes. In RA-Dec mode this sets Right
|
|
Ascension and can be varied from 0 to 23:59:40 hours, in steps of 20
|
|
seconds. The Az/RA scale may also be changed using the keypad Left and
|
|
Right arrow keys (make sure your NumLock is off). Using the key alone
|
|
moves by 2%, with Shift moves 10%. </div>
|
|
<a name="SkyView_trails"></a>
|
|
<h2><a class="mozTocH3" name="mozTocId444921"></a> 5.4 Trails</h2>
|
|
<div style="margin-left: 40px;">
|
|
<p>The location of any object on the Sky view may be computed at
|
|
regular intervals and displayed by setting up a sky trail. Use the <a
|
|
href="#Trails">Trails Setup</a> window to select the interval,
|
|
number of steps, formatting details and which steps you would like
|
|
annotated. The trail setup window is accessed from the popup which
|
|
appears when the third mouse button is activated when the cursor is
|
|
near an object. Any number of objects may have trails.</p>
|
|
<p>The trail is created by computing the location of the object at
|
|
several intervals. Each new location will be drawn with a small mark
|
|
and connected with a line to its previous location. The trails
|
|
remain correct if the display coordinate system is changed. Trails
|
|
may be turned on or off without loss of trail information. Trail
|
|
information is discarded if a trail is turned off when a new Main
|
|
window Update is performed. If any point on a trail is selected
|
|
using the third mouse button the information displayed is as per the
|
|
object at that time. The times displayed next to trailed objects are in
|
|
accord with the setting of <a href="#MainMenu_preferences">Preferences</a> ->
|
|
Time zone.
|
|
Trail information is <em>not</em> subject to the
|
|
constraints in the <a href="#SkyView_filter">Filter</a> window, <i>i.e.</i>,
|
|
trailed objects are always shown.</p>
|
|
<p>Note that in Alt-Az mode, each trailed location is positioned on
|
|
the display according to the sky at the current moment. But because
|
|
of diurnal motion these trails are not useful for comparison with
|
|
the background of fixed stars. Use the RA-Dec mode for that. This is
|
|
so important (and easily overlooked) that you will see a reminder
|
|
notice to this effect the first (and only) time you create and
|
|
display a trail in Alt-Az mode.</p>
|
|
<p>Finally, be sure to recompute any trails if you change any of
|
|
the preferences or circumstances in the Main window.</p>
|
|
</div>
|
|
<a name="SkyView_control"></a>
|
|
<h2><a class="mozTocH1" name="mozTocId564189"></a> 5.5 Sky View Control
|
|
menu</h2>
|
|
This is a summary of the Sky View Control menu. Details follow.<br>
|
|
<br>
|
|
<span style="font-weight: bold;">Options...</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This brings up a window with several
|
|
choices effecting the way the scene is drawn. See <a
|
|
href="#SkyView_ops">Options</a>. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Filter...</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This allows selecting the types and
|
|
magnitude ranges of objects to display. See <a href="#SkyView_filter">Filter</a>.
|
|
</div>
|
|
<br>
|
|
<span style="font-weight: bold;">Print...</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This allows printing the current Sky
|
|
view or saving it to a file. If an image is currently being
|
|
displayed, it will also be part of the print image. See <a
|
|
href="#Print">Printing</a>. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">List...</span><br>
|
|
<div style="margin-left: 40px;"></div>
|
|
<div style="margin-left: 40px;"> This brings up a window that allows
|
|
saving the objects currently displayed in the Sky View to a file.
|
|
See <a href="#SkyView_list">List</a>. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Horizon...</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This activates the Horizon setup
|
|
window
|
|
where you can define new or load existing horizon profiles. To
|
|
actually display the Horizon profile, turn on the toggle under
|
|
Option. See <a href="#Horizon">Horizon</a>. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Field Stars...</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This activates the Field Star setup
|
|
window. To display Field Stars, turn on the toggle under Options.
|
|
See <a href="#FieldStars">Field stars</a>. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Favorites ...</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This activates the Favorites setup
|
|
window. See <a href="#Favorites">Favorites</a>. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Eyepieces...</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This brings up a window which allows
|
|
you to specify the shape, size, rotation and style of the next
|
|
eyepiece to be created. See <a href="#SkyView_eyepieces">Eyepieces</a>.
|
|
Whether eyepieces are shown at all is controlled by the <span
|
|
style="font-family: monospace;">Control » Options »
|
|
Eyepieces</span> option; see <a href="#SkyView_ops">Options</a>. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Coordinates...</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This brings up a simple dialog which
|
|
allows you to type in (or copy/paste) and convert among several
|
|
common coordinate systems used in astronomy. The coordinates may be
|
|
set from or used to repoint the Sky View. See <a href="#Coord_conv">Coordinate
|
|
converter</a>. </div>
|
|
<span style="font-weight: bold;"><br>
|
|
User annotation...</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This selection brings up a window
|
|
which
|
|
allows text and lines to be drawn over the image. See <a
|
|
href="#Annotation">Annotation</a>. </div>
|
|
<br>
|
|
<b>Add to movie...</b><br>
|
|
<blockquote>This selection brings up a window to allow adding the
|
|
current Sky view to a <a href="xephem.html#Movie">movie loop</a>.<br>
|
|
</blockquote>
|
|
<span style="font-weight: bold;">Tracking<br>
|
|
<br>
|
|
</span>
|
|
<div style="margin-left: 40px;"> Tracking in this context refers to
|
|
whether the pointing direction of the Sky View will automatically be
|
|
changed each time an Update occurs from the Main window such that
|
|
the tracked object will remain centered on the display. The object to
|
|
be
|
|
tracked is selected by using the <span style="font-weight: bold;">Track</span>
|
|
option in its popup menu, as described elsewhere. When this toggle
|
|
button is sensitive and pushed-in it means that tracking is active for
|
|
one object. The tracked object will be marked with an × on the
|
|
display after each Update. If this toggle button is selected while it
|
|
is
|
|
sensitive, it turns tracking off. This is a convenient alternate method
|
|
to turn off object tracking without having to find the exact object
|
|
being tracked and use its popup Track control. When this toggle
|
|
button is insensitive and popped-out, it means that object tracking
|
|
is not active; it does nothing when selected while insensitive. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Close:</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This causes the Sky view and all
|
|
supporting windows to go away. </div>
|
|
<a name="SkyView_ops"></a>
|
|
<h3><a class="mozTocH1" name="mozTocId515599"></a> 5.5.1 Options</h3>
|
|
<h4><a class="mozTocH4" name="mozTocId267321"></a> 5.5.1.1 <span
|
|
style="font-weight: bold;"><img alt=""
|
|
src="png/sky-control-options.png" align="right" height="684"
|
|
width="148">Display mode:</span></h4>
|
|
<div style="margin-left: 40px;"> Alt-Az<br>
|
|
RA-Dec<br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This pair selects whether the display
|
|
coordinate system is Altitude-Azimuth or Right
|
|
Ascension-Declination. While in Alt/Az mode the display is always
|
|
topocentric; while in RA/Dec mode the display coordinate system
|
|
depends on the Equatorial preference and Equinox settings in the
|
|
Main window. </div>
|
|
</div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Sphere<br>
|
|
Cylinder<br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This pair selects whether the display
|
|
is projected onto a sphere or a cylinder. The advantage of the
|
|
sphere is that it mimics the real sky. The advantage of the
|
|
cylinder is it shows the entire universe at once. </div>
|
|
</div>
|
|
<h4><a class="mozTocH4" name="mozTocId289736"></a> 5.5.1.2 <span
|
|
style="font-weight: bold;">Grid Control:</span></h4>
|
|
<div style="margin-left: 40px;"> This group of controls allows you to
|
|
specify the details of an overlay coordinate grid.<br>
|
|
<br>
|
|
Grid<br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Toggles the grid on or off. </div>
|
|
<br>
|
|
Auto<br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> If on, the size of the grid steps will
|
|
be determined automatically and shown in the text fields beneath;
|
|
if it is off, then step sizes are determined from the values in
|
|
the text fields. Typing into either field then pressing Enter will also
|
|
turn off Auto and immediately display the grid with the new step
|
|
size. </div>
|
|
<br>
|
|
Alt-Az<br>
|
|
RA-Dec<br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This pair selects in which coordinate
|
|
system the grid will be drawn. </div>
|
|
<br>
|
|
Label<br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Selects whether the grid will be
|
|
labeled. </div>
|
|
</div>
|
|
<br>
|
|
<h4><a class="mozTocH4" name="mozTocId623583"></a> 5.5.1.3 <span
|
|
style="font-weight: bold;">View Options:</span></h4>
|
|
<div style="margin-left: 40px;"> Just dots </div>
|
|
<br>
|
|
<div style="margin-left: 80px;"> This toggle effects how stars are
|
|
shown. When the toggle is pushed in, all stars are displayed simply
|
|
as dots of various sizes. When the toggle is released, each type of
|
|
star is displayed with a unique schematic symbol. These symbols may
|
|
be reviewed from the <a href="#SkyView_filter">Filter</a> window. </div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Flip Left/Right </div>
|
|
<div style="margin-left: 40px;"> Flip Top/Bottom </div>
|
|
<br>
|
|
<div style="margin-left: 80px;"> These toggle whether the display is
|
|
shown with a flip in the left/right or the top/bottom directions,
|
|
respectively. </div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Equatorial plane </div>
|
|
<br>
|
|
<div style="margin-left: 80px;"> This toggles whether a red 3:6 dashed
|
|
line is shown along the Earth's equator projected onto the celestial
|
|
sphere. The North and South celestial poles are marked and labeled as
|
|
NCP and SCP, respectively.<br>
|
|
</div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Ecliptic plane </div>
|
|
<br>
|
|
<div style="margin-left: 80px;"> This toggles whether a red 2:2 dotted
|
|
line is shown along the ecliptic. The ecliptic is the plane of the
|
|
Earth's orbit or, as seen from Earth, the path of the Sun and the
|
|
approximate path of the planets across the sky. The anti-solar point
|
|
is marked with a small open circle. The Vernal and Autumnal equinoxes
|
|
and Summer and Winter solstice locations are marked and labeled as VEq,
|
|
AEq, SS and WS respectively. The North and South eclipic poles are
|
|
marked and labeled as
|
|
NEP and SEP, respectively.<br>
|
|
<br>
|
|
The
|
|
edges of umbra/penumbra of
|
|
Earth are marked with open circles. If <span
|
|
style="font-family: monospace;">Preferences » Equatorial</span>
|
|
is set to Topocentric, the umbra/penumbra are projected at the current
|
|
distance of the Moon and corrected for parallax; if set to
|
|
Geocentric they are projected at infinity. </div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Galactic plane </div>
|
|
<br>
|
|
<div style="margin-left: 80px;"> This toggles whether a red 1:4 dotted
|
|
line is shown along the galactic equator. The North and South galactic
|
|
poles are marked and labeled as NGP and SGP, respecively. The galactic
|
|
center is marked and labeled as GC. The outline of the
|
|
Milky Way boundary is also shown.</div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Eyepieces </div>
|
|
<br>
|
|
<div style="margin-left: 80px;"> This toggles whether eyepieces are
|
|
drawn on the Sky view, if and when any are placed. <a
|
|
href="#SkyView_eyepieces">Eyepieces</a> are placed on the Sky view by
|
|
using the <span style="font-weight: bold;">Place eyepiece</span>
|
|
control in the popup menu activated by the right mouse button. The
|
|
shape and style of eyepieces is defined in the <span
|
|
style="font-family: monospace;">Control » Eyepieces</span>
|
|
window. Eyepieces are only drawn if they fit entirely within the Sky
|
|
View. This selection is automatically activated when an eyepiece is
|
|
placed. </div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Magnitude key </div>
|
|
<br>
|
|
<div style="margin-left: 80px;"> This toggles whether to display a
|
|
chart
|
|
in the lower left corner showing the correspondence between dot size
|
|
and star magnitude. The scale is automatically turned off each time
|
|
an image is first displayed. </div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Compass rose </div>
|
|
<br>
|
|
<div style="margin-left: 80px;"> This toggles whether two symbols to
|
|
indicate the cardinal directions at the center of the Sky View in
|
|
each Display mode are drawn in the lower right corner. The symbol on
|
|
the right always shows the current mode, the symbol to its left the
|
|
opposite mode. The one labeled with <b>Z</b> and <b>R</b> indicates
|
|
the
|
|
local horizontal directions toward the Zenith and toward the Right; the
|
|
one labeled with <b>N</b> and <b>W</b> indicates equatorial North and
|
|
West. The symbols are not drawn near their respective poles. </div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Auto magnitude </div>
|
|
<br>
|
|
<div style="margin-left: 80px;"> When this toggle is active, the
|
|
faintest magnitudes and dot step size will automatically be set to
|
|
something reasonable based on the field of view. This option is
|
|
automatically turned on whenever the FOV changes for any reason,
|
|
unless it was turned off manually. Note that initial resource values
|
|
for faintest magnitudes and dot step size will not be honored unless
|
|
the
|
|
initial resource value for automag is also off.</div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Field Stars </div>
|
|
<br>
|
|
<div style="margin-left: 80px;"> This toggles whether <a
|
|
href="#FieldStars">Field stars</a> are automatically loaded and
|
|
displayed if the position, field of view, limiting magnitude or time
|
|
changes significantly. This selection turns itself off if any
|
|
difficulties ever arise in retrieving field stars. </div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Live dragging </div>
|
|
<br>
|
|
<div style="margin-left: 80px;"> This toggles whether the graphics are
|
|
redrawn in real time as the various scale controls are being slid,
|
|
or whether the graphics are not redrawn until the mouse is released.
|
|
What works best for you depends on the speed of the computer, display
|
|
and data bandwidth. If the system is fast enough, turning this on can
|
|
produce dramatic results. </div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Horizon map </div>
|
|
<br>
|
|
<div style="margin-left: 80px;"> This toggles whether to display the
|
|
local horizon profile on the Sky View and
|
|
whether objects below the horizon are drawn. The profile
|
|
linearly interpolates between points in the defining file. See <a
|
|
href="#Horizon">Horizon</a>. </div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Clipping </div>
|
|
<br>
|
|
<div style="margin-left: 80px;"> This toggles whether objects
|
|
which are below the horizon are drawn. This has no effect if no
|
|
horizon is displayed.<br>
|
|
</div>
|
|
<h4><a class="mozTocH4" name="mozTocId708731"></a> 5.5.1.4 <span
|
|
style="font-weight: bold;">Constellation:<br>
|
|
</span></h4>
|
|
<div style="margin-left: 40px;"> File name<br>
|
|
</div>
|
|
<br>
|
|
<div style="margin-left: 80px;">This drop-down selection allows you to
|
|
select the file that defines constellation figures. The files supplied
|
|
with XEphem are HAReyfigs.csf and classicfigs.csf to define the figures
|
|
defined by H. A. Rey or the classic definitions, respectively. The
|
|
files shown for possible selection are those files ending with the .csf
|
|
suffix in the Shared and Private directories.<br>
|
|
<br>
|
|
The definition file must contain exactly one figure for each of the 89
|
|
constellations. Leading white space, blank lines and lines beginning
|
|
with # are ignored. Each figure definition begins with a line
|
|
containing just its name followed by one or more lines of the form:<br>
|
|
drawcode ra dec [comment]<br>
|
|
where<br>
|
|
drawcode is a numeric value indicating a drawing
|
|
instruction as follows:<br>
|
|
0 move to ra dec<br>
|
|
1 draw solid line to ra dec<br>
|
|
2 draw dashed line to ra dec<br>
|
|
ra is decimal hours or sexigesimal h:m:s<br>
|
|
dec is decimal degrees or sexigesimal d:m:s<br>
|
|
the remainder of the line is ignored and may be any
|
|
comments, typical is the name of a star being drawn to.<br>
|
|
<br>
|
|
</div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Figures<br>
|
|
Boundaries<br>
|
|
</div>
|
|
<br>
|
|
<div style="margin-left: 80px;"> This pair controls whether to show
|
|
constellation figures and/or constellation boundaries.<br>
|
|
<br>
|
|
</div>
|
|
<div style="margin-left: 40px;"> Full Names </div>
|
|
<div style="margin-left: 40px;"> Abbreviations </div>
|
|
<br>
|
|
<div style="margin-left: 80px;"> This radio pair controls whether and
|
|
how
|
|
constellation names are shown. The choices are full names, their
|
|
3-letter abbreviations or neither. </div>
|
|
<h4><a class="mozTocH4" name="mozTocId353932"></a> 5.5.1.5 Labeling:</h4>
|
|
<div style="margin-left: 40px;"> This portion controls labeling
|
|
options.
|
|
The sliders select how many of the brightest objects to label in
|
|
each of four categories. The count ranges from 0 on the left to All
|
|
on the right.<br>
|
|
<br>
|
|
The label itself may consist of the Name or Magnitude or both,
|
|
depending on the state of the two buttons in the columns marked N
|
|
and M to the left of each scale. If Names and Magnitudes are both
|
|
turned on then the magnitude is drawn to the right of the name
|
|
surrounded by parentheses. Magnitudes are always drawn to the
|
|
nearest 1/10 with the decimal point removed.<br>
|
|
<br>
|
|
Trailed entries and objects marked for Persistent Label do not
|
|
contribute towards the brightest count. </div>
|
|
<br>
|
|
<a name="SkyView_filter"></a>
|
|
<h3><a class="mozTocH1" name="mozTocId326208"></a> 5.5.2 Filter</h3>
|
|
<br>
|
|
<img style="width: 255px; height: 510px;" alt=""
|
|
src="png/sky-control-filter.png" align="right" height="509" hspace="20"
|
|
width="255">This window lists all classes of
|
|
objects
|
|
supported by XEphem. Using the Filter window, you may select which
|
|
classes of objects are displayed on the Sky view window. For
|
|
reference, the Filter window also contains the schematic symbol for
|
|
each type of object, and its code when used in a database file. The
|
|
symbol displayed for each class of object is that which will be used to
|
|
represent the object in the Sky view, unless <span
|
|
style="font-family: monospace;">Control » Options » Just</span>
|
|
<span style="font-family: monospace;">dots</span> is selected. Note
|
|
that the symbol used to draw an Elliptical object in the Sky View is
|
|
the same as that for objects of type Hyperbolic and Parabolic if the
|
|
name of the object begins with "C/" (presumed to denote a comet).<br>
|
|
<br>
|
|
Three scales near the bottom of the Filter window control the faintest
|
|
magnitude limit to be displayed for Stars, Solar system and Deep sky
|
|
objects. Note that trails and persistent labels are not subject to the
|
|
faint magnitude limits.<br>
|
|
<br>
|
|
The diameter of the symbol drawn in the Sky View is the larger of the
|
|
object's actual size at the current window scale (if a size is
|
|
specified in the database entry for the object) or a size that is
|
|
proportional to the difference between the object's magnitude and the
|
|
current faintest magnitude setting.<br>
|
|
<br>
|
|
The fourth scale in the lower left selects the number of magnitudes
|
|
binned in each dot size. Values larger than 1 are helpful for showing
|
|
very large ranges of magnitudes.<br>
|
|
<br>
|
|
Several push buttons appear across the bottom of the Filter window
|
|
which have the usual effects: Selecting <span
|
|
style="font-weight: bold;">Apply</span>
|
|
updates the Sky display according to the desired selection. Selecting <span
|
|
style="font-weight: bold;">Ok</span> does the same thing but also
|
|
closes the Filter window. <span style="font-weight: bold;">All</span>
|
|
turns on all types. <span style="font-weight: bold;">Toggle</span>
|
|
swaps
|
|
which filters and Or and Off. <span style="font-weight: bold;">Reset</span>
|
|
will return the state of all Filter controls to their state when this
|
|
window first appeared or the most recent Apply.<br clear="all">
|
|
<h3><a class="mozTocH4" name="mozTocId35744"></a> 5.5.3 <a name="Print_"></a>Print</h3>
|
|
This allows printing the current Sky view or saving it to a file. If
|
|
an image is currently being displayed, it will also be part of the
|
|
print image. See <a href="#Print">Printing</a>.<br>
|
|
<br>
|
|
<a name="SkyView_list"></a>
|
|
<h3><a class="mozTocH1" name="mozTocId864598"></a> 5.5.4 List</h3>
|
|
<div style="text-align: center;"> <img
|
|
style="width: 461px; height: 492px;" alt="" title=""
|
|
src="png/sky-control-list.png" align="middle"><br>
|
|
</div>
|
|
<br clear="all">
|
|
This window lists, sorts and writes the objects currently displayed
|
|
in the Sky View to a file. Basing the list on the Sky View allows the
|
|
selection criteria to use the full power of the Options and Filters
|
|
controls as well as the region of the sky as defined by the center and
|
|
field of view. If you wish to include all objects without regard to
|
|
position, use the Cylindrical project mode, set RA-Dec, FOV 180, Dec 0
|
|
and resize the Sky View window to show the entire universe.<br>
|
|
<br>
|
|
At the top, the format of the file created may be specified in either
|
|
of two formats. The .edb format saves the objects in the XEphem
|
|
catalog format. This is handy for using the XEphem filtering options
|
|
to create custom catalogs. The text format is a columnar listing. The
|
|
columns that are printed are the same as those currently selected in
|
|
the Data Table, printed to the precision specified in the <a
|
|
href="#MainMenu_preferences">Preferences</a>. A convenient button is
|
|
provided to bring up the Date Table setup window. Note that a column
|
|
need not be printed to be used for sorting, although it would seem
|
|
unusual to do so.<br>
|
|
<br>
|
|
The center section lists several fields that may used for sorting the
|
|
list. Pick each field in the order you wish to sort the list. If you
|
|
wish to make a change to the order, you may Undo one at a time back to
|
|
the beginning or Clear the entire sequence and begin again.<br>
|
|
<br>
|
|
The bottom section is a text field which (will) show the results of
|
|
the sort. This text field is fully editable, so you may delete specific
|
|
objects, add comments and so on as desired. N.B. If you have chosen
|
|
the .edb format, no checks are made that your edits have made the
|
|
format illegal.<br>
|
|
<br>
|
|
Pressing the right mouse button over the text field will bring up a
|
|
popup menu, if a valid object name is found at the beginning of the
|
|
line under the cursor. This popup has buttons to Delete the object on
|
|
the current line from the list and Mark the object on the Sky View.<br>
|
|
<br>
|
|
Across the bottom are several controls.<br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> <span style="font-weight: bold;">Save</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This writes the text field exactly as
|
|
it now appears to the file named at the right of the format
|
|
checked at the top. N.B. No check is made that the format and the
|
|
extension agree. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Sort</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This rebuilds the list according to
|
|
the
|
|
current settings. Use this after changing something in the Sky
|
|
View, or after changing the format or sort settings here. </div>
|
|
<br>
|
|
<a name="Horizon"></a> </div>
|
|
<h3><a class="mozTocH1" name="mozTocId669677"></a> 5.5.5 Horizon</h3>
|
|
<img style="width: 237px; height: 151px;" alt="" title=""
|
|
src="png/sky-control-horizon.png" align="right" hspace="20"> XEphem
|
|
allows you to create a file describing your local horizon. This window
|
|
gives you two ways to define your local horizon, and a handy way to
|
|
edit and save a horizon description.
|
|
One way to define a horizon is just to specify one altitude that will
|
|
be used
|
|
at all azimuths. To use this method, type the desired altitude in the
|
|
field provided, then type Enter or toggle the button labeled <span
|
|
style="font-weight: bold;">Constant</span> On.<br>
|
|
<br>
|
|
The other way is to draw your actual horizon profile interactively as
|
|
follows:<br>
|
|
<ol>
|
|
<li>Set the Sky View to display Alt-Az mode;</li>
|
|
<li>set Az to 0, Alt to 90, FOV to 180 so you see your entire sky;</li>
|
|
<li>click on <span style="font-weight: bold;">Edit with mouse</span>;</li>
|
|
<li>draw your horizon with the mouse;</li>
|
|
<li>when finished turn Edit with mouse back off;<br>
|
|
</li>
|
|
<li>enter a file name;</li>
|
|
<li>click <span style="font-weight: bold;">Save</span>.<br>
|
|
</li>
|
|
</ol>
|
|
Editing can in fact be performed in any mode but the above setup is the
|
|
most natural. Reload the profile later using <span
|
|
style="font-weight: bold;">Load</span>.
|
|
As many profiles can be stored as desired. For example, if you
|
|
observe from several sites, you can have a profile for each.<br>
|
|
<blockquote><span style="font-weight: bold;">File format</span><br>
|
|
<span style="font-weight: bold;"></span><br>
|
|
<span style="font-weight: bold;"></span>The Horizon profile file
|
|
format (suffix <tt>.hzn</tt>) and its use by
|
|
XEphem are defined as follows:<br>
|
|
</blockquote>
|
|
<blockquote>
|
|
<ul>
|
|
<li>Each line should contain exactly two numbers separated by
|
|
spaces.</li>
|
|
<li>The first number is the azimuth, expressed as degrees East of
|
|
North.</li>
|
|
<li>Azimuth values range from 0 up to 360 degrees. Any values
|
|
outside
|
|
this range have 360 added or subtracted until they fall in this
|
|
range.</li>
|
|
<li>The lines need not be sorted by Azimuth, although they will be
|
|
sorted when used; thus the horizon map can never cross itself.</li>
|
|
<li>If the file does not include the full range of Azimuths, the
|
|
end points will be connected automatically.</li>
|
|
<li>It is ok to specify just one point (at any Azimuth). This will
|
|
result in a flat horizon all the way around at the specified
|
|
Altitude. This is functionally equivalent to using the Constant
|
|
method.</li>
|
|
<li>The second number is degrees above horizontal.</li>
|
|
<li>XEphem linearly interpolates as necessary when drawing between
|
|
the Az and Alt values in the file.</li>
|
|
<li>Lines of any other form are ignored.</li>
|
|
</ul>
|
|
</blockquote>
|
|
<h3><a class="mozTocH4" name="mozTocId949206"></a> 5.5.6 <a name="Field_Stars_"></a><span
|
|
style="font-weight: bold;">Field Stars</span></h3>
|
|
<div style="margin-left: 40px;"> This activates the Field Star setup
|
|
window. To display Field Stars, turn on the toggle under Options.
|
|
See <a href="#FieldStars">Field stars</a>. </div>
|
|
<h3><a class="mozTocH4" name="mozTocId411561"></a> 5.5.7 <span
|
|
style="font-weight: bold;">Favorites</span></h3>
|
|
<div style="margin-left: 40px;"> This activates the Favorites setup
|
|
window. See <a href="#Favorites">Favorites</a>. </div>
|
|
<br>
|
|
<a name="SkyView_eyepieces"></a>
|
|
<h3><a class="mozTocH1" name="mozTocId82697"></a> 5.5.8 Eyepieces</h3>
|
|
<img alt="" src="png/sky-control-eyepieces.png" align="right"
|
|
height="564" hspace="10" vspace="10" width="326">This
|
|
window allows you to specify the shape, rotation angle, size and style
|
|
of the next eyepiece marker to be placed in the Sky View. These
|
|
markers are useful to show the view through your eyepiece, simulate
|
|
the view of a CCD camera, or as simple annotation markers for any
|
|
desired purpose. Symbology on the map will show through the eyepieces,
|
|
even when they are specified as solid.
|
|
<br>
|
|
<br>
|
|
Note that this window controls the style of the next eyepiece to be
|
|
created. To actually place an eyepiece, place the mouse over the Sky
|
|
view where you want the center to be located and press the right
|
|
button. A popup menu will appear. Slide down the menu and release over <span
|
|
style="font-weight: bold;">Place eyepiece</span>. When an eyepieces is
|
|
place on the sky, both the RA-Dec and Alt-Az of the location are saved
|
|
and the set
|
|
matching the Display mode is used when the eyepiece is drawn on the
|
|
Sky View. In this way eyepieces are fixed in both coordinate systems.<br>
|
|
<br>
|
|
<b>Set next eyepiece ...</b><br>
|
|
<blockquote>Across the top are three sliders which set the <span
|
|
style="font-weight: bold;">W</span>idth, <span
|
|
style="font-weight: bold;">H</span>eight and <span
|
|
style="font-weight: bold;">A</span>ngle of the next eyepiece. Width
|
|
and Height are shown in units of degrees:minutes.
|
|
The interpretation of the rotation angle depends on the
|
|
current display mode of the Sky View at the moment a new eyepiece is
|
|
placed. When in Alt/Az mode, the angle is away from a line through the
|
|
Zenith, and when in RA/Dec mode the angle is away from the North
|
|
Celestial Pole. In both cases, the units are degrees.
|
|
<br>
|
|
<br>
|
|
Below them is a toggle that will <span style="font-weight: bold;">Lock</span>
|
|
the W and H sliders so they move together. This makes it easy to
|
|
create eyepiece shapes that are perfectly round or square.<br>
|
|
<br>
|
|
As a special convenience for and in deference to, there is a toggle
|
|
which will create three open circles spaced to match the view through
|
|
the <span style="font-weight: bold;">Telrad</span> unit power finder.
|
|
The circles are 0.5, 2 and 4 degrees in diameter. As long as this
|
|
special toggle is pushed in, the other controls are made insensitive
|
|
to avoid interfering with the preset values for the Telrad.<br>
|
|
<br>
|
|
Next below are pairs of toggle buttons to select the Shape and Style
|
|
of the next eyepiece. <span style="font-weight: bold;">Elliptical</span>
|
|
and <span style="font-weight: bold;">Rectangular</span> refer to
|
|
circles
|
|
and squares. <span style="font-weight: bold;">Solid</span> and <span
|
|
style="font-weight: bold;">Outline</span> refer to whether the shape
|
|
will be filled in or just drawn as a border.<br>
|
|
</blockquote>
|
|
<b>Field-of-View Calculators</b><br>
|
|
<blockquote>In the central portion of the Eyepiece window are two <span
|
|
style="font-weight: bold;">calculators</span> that can be used to
|
|
compute the sky angle of an optical system in two ways. The first
|
|
method uses the net focal length of the entire optical system and a
|
|
linear size on the focal plane. The technique is handy for CCD users
|
|
who want to find the sky angle subtended by each pixel or the entire
|
|
detector. Another good use of this form is for photographers using
|
|
film to find the amount of sky that will fit on their film. To cover
|
|
this wide range of applications, the measures may be specified in any
|
|
of several common units by adding the appropriate suffix. Default
|
|
units are shown in parentheses.<br>
|
|
<br>
|
|
The second calculator uses the apparent field of view while looking
|
|
into an eyepiece and divides this by the magnification, which in turn
|
|
is found from the ratio of focal lengths for the primary mirror and
|
|
the eyepiece. Typical eyepieces provide about 45 degrees apparent
|
|
fields of view, and some premium ones can go to 60 degrees or more.
|
|
After using either method, the resulting sky angle can be assigned to
|
|
the Width or Height scale for the next eyepiece by using the Set W and
|
|
H buttons to the right.<br>
|
|
</blockquote>
|
|
<b>Saving Eyepiece Definitions</b><br>
|
|
<blockquote>This portion of the Eyepieces window allows you to <b>Add</b>
|
|
the current eyepiece settings to a list of favorites. A simple
|
|
name is chosen automatically but you may change this to be more
|
|
meaningful to you. Each such eyepiece may be <span
|
|
style="font-weight: bold;">Del</span>eted from the set or put to <span
|
|
style="font-weight: bold;">Use</span> by using the buttons on the
|
|
left. To the right of each eyepiece is a reminder of its width, height
|
|
and a code letter for its shape and size.<br>
|
|
<br>
|
|
The buttons below the table of favorite eyepieces allow you to <b>Save</b>
|
|
and later <b>Load</b> the table to a file. These files have the
|
|
extension <b>.epd</b>. When saving, the new file is always created in
|
|
the Private directory. When
|
|
loading, files with this suffix are first checked for in the Private
|
|
directory and if
|
|
not found in the Shared directory. The suffix is automatically added if
|
|
not entered in the file name field. The file named in the Save field is
|
|
also the file that is automatically loaded when XEphem starts. This
|
|
file name can be saved in the <tt>Preferences <span
|
|
style="font-family: monospace;">»</span> Save </tt>window in
|
|
the Skyview -- Eyepieces section as EyePDefFile.<br>
|
|
</blockquote>
|
|
<b>Saving Sky View Eyepiece Placements</b><br>
|
|
<blockquote><b></b>
|
|
This portion of the Eyepieces window allows you to <b>Save</b> and
|
|
later <b>Load</b> the set of eyepieces currently defined on the Sky
|
|
View to a file. These files have the extension <b>.epp</b>. When
|
|
saving, the new file is always created in
|
|
the Private directory. When
|
|
loading, files with this suffix are first checked for in the Private
|
|
directory and if
|
|
not found in the Shared directory. The suffix is automatically added if
|
|
not entered in the file name field. The file named in the Save field is
|
|
also the file that is automatically loaded when XEphem starts. This
|
|
file name can be saved in the <tt>Preferences <span
|
|
style="font-family: monospace;">»</span> Save </tt>window in
|
|
the Skyview -- Eyepieces section as EyePPosFile.<br>
|
|
</blockquote>
|
|
<b>Delete all placed eyepieces<br>
|
|
</b>
|
|
<blockquote>After at least one eyepiece has been placed in the Sky
|
|
View, a button
|
|
at the bottom of this window will become available to permanently <span
|
|
style="font-weight: bold;">Delete all placed eyepieces</span>
|
|
currently anywhere on the Sky View. You may also delete them
|
|
individually from the Sky View from the right-click popup or if you
|
|
just want to temporarily turn all Eyepieces off and back on later, use
|
|
the Eyepieces control in the <span style="font-family: monospace;">Control
|
|
» Options</span> window.<br>
|
|
</blockquote>
|
|
<b>Close</b><br>
|
|
<blockquote>Across the bottom are buttons to <span
|
|
style="font-weight: bold;">Close</span>
|
|
the window and <span style="font-weight: bold;">Help</span> to get
|
|
more
|
|
information. Closing the window has no effect on eyepieces already
|
|
placed in the Sky View.<span style="font-weight: bold;"></span><br>
|
|
<span style="font-weight: bold;"></span></blockquote>
|
|
<h3><a class="mozTocH4" name="mozTocId931036"></a> 5.5.9 <span
|
|
style="font-weight: bold;">Coordinates</span></h3>
|
|
<div style="margin-left: 40px;"> This brings up a simple dialog which
|
|
allows you to type in (or copy/paste) and convert among several
|
|
common coordinate systems used in astronomy. The coordinates may be
|
|
set from or used to repoint the Sky View. See <a href="#Coord_conv">Coordinate
|
|
converter</a>. </div>
|
|
<h3><a class="mozTocH4" name="mozTocId287757"></a> 5.5.10 <a
|
|
name="User_annotation_"></a> <span style="font-weight: bold;">User
|
|
annotation</span></h3>
|
|
<div style="margin-left: 40px;"> This selection brings up a window
|
|
which
|
|
allows text and lines to be drawn over the image. See <a
|
|
href="#Annotation">Annotation</a>. </div>
|
|
<br>
|
|
<a name="SkyView_images"></a>
|
|
<h2><a class="mozTocH1" name="mozTocId505331"></a> 5.6 Sky View Images menu</h2>
|
|
The Images menu can bring up three windows.<br>
|
|
<br>
|
|
<span style="font-weight: bold;">Load and save...</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This window controls loading local
|
|
FITS
|
|
files, downloading them from the Net, and saving them locally. </div>
|
|
<span style="font-weight: bold;"><br>
|
|
Analysis tools...</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This window provides a variety of
|
|
image
|
|
analysis and processing tools. Settings made in this window can also
|
|
effect what the mouse does in the Sky View when an image is being
|
|
displayed. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">WCS Solver...</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This window provides a means to add
|
|
World Coordinate System headers to a FITS file. With WCS, XEphem
|
|
(and many other programs) can compute the RA and Dec of each pixel
|
|
in the file, not just its X and Y pixel coordinates. This capability
|
|
opens the door to many interesting possibilities. The algorithm
|
|
performs
|
|
a pattern match between the star-like artifacts in the image and the
|
|
GSC
|
|
and/or USNO star catalogs. </div>
|
|
<a name="Sky_FITS"></a>
|
|
<h3><a class="mozTocH1" name="mozTocId164101"></a> 5.6.1 Load and Save FITS
|
|
images<br>
|
|
</h3>
|
|
<img style="width: 300px; height: 500px;" alt="" title=""
|
|
src="png/sky-images-fits.png" align="right" hspace="20"> This
|
|
window allows you to display a FITS file in the Sky View window. You
|
|
may display local files or download the Digital Sky Survey directly
|
|
from the Internet. The image is resized to match the size of the Sky
|
|
View window. Once an image is displayed, all graphical features of the
|
|
Sky View are available, such as grids and labeling objects loaded in
|
|
the XEphem database. Most of these features require that WCS headers
|
|
be present in the image. XEphem can help create these using the <a
|
|
href="#SkyIP_WCS">WCS Solver</a> tool.<br>
|
|
<br>
|
|
Resizing the window will change the size of the scrolled text
|
|
area displaying the FITS header fields.<br>
|
|
<br>
|
|
<span style="font-weight: bold;">Open FITS file</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;">Clicking on the option menu will
|
|
display a list of all FITS files in the <a href="#SharedPrivateDirs">Private
|
|
and Shared</a> directories in a popup menu. All files with the name
|
|
extension .fts, .fits, or .fit will be included. Clicking on a file in
|
|
the popup list will display it.<br>
|
|
</div>
|
|
<div style="margin-left: 40px;"> <br>
|
|
</div>
|
|
<span style="font-weight: bold;">Download</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This button heads up the section for
|
|
downloading Digital Sky Survey images from the Internet You may
|
|
choose generations 1 and 2, and either Red or Blue filters for the
|
|
latter. The DSS is maintained by the Space Telescope Science
|
|
Institute, STScI, in the United States or the European Southern
|
|
Observatory, ESO, research facility in Germany. The image data from
|
|
either site is identical, so choosing which to use depends only on
|
|
availability and whichever is faster for you.<br>
|
|
<br>
|
|
The size and position of the image are that of the current Sky View
|
|
settings, but the size is limited to 30 arc minutes by agreement
|
|
with each institution. Before attempting a download, use the <span
|
|
style="font-family: monospace;">File » Network setup</span>
|
|
window off the Main menubar to configure your Internet connection.<br>
|
|
<br>
|
|
Clicking Display will begin the download. A progress meter will display
|
|
remaining time. A Stop window is provided if you care to abandon the
|
|
effort. The header of the http server response message is in the
|
|
Main <span style="font-family: monospace;">File » Syetem Log</span>
|
|
window; check there if an error occurs. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">FITS Header:</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This section consists mainly of a
|
|
scrolled text area which shows each field in the FITS header.<br>
|
|
<br>
|
|
If the
|
|
header contains any of the fields EPOCH, JD or DATE-OBS then the
|
|
date of the observation is displayed above the header. The button
|
|
labeled <span style="font-weight: bold;">Set time</span> will also
|
|
come
|
|
alive which allows setting the main XEphem time and date to this
|
|
value. This is handy when checking for asteroids, comets or using
|
|
the proper motion catalogs with an image. EPOCH must be a decimal year;
|
|
JD must be a decimal Julian Date; or DATE-OBS must be either in ISO
|
|
8601
|
|
format (YYYY-MM-DDTHH:MM:SS), YYYY[/-]MM[/-]DD, or MM[/-]DD[/-]YY
|
|
where YY is assumed to be the number of years since 2000 if less than
|
|
50 otherwise years since 1900.<br>
|
|
<br>
|
|
In order to be displayed by XEphem, the header in a FITS file must
|
|
contain at least the mandatory fields SIMPLE, BITPIX, NAXIS, NAXIS1,
|
|
NAXIS2 and END. Only files with BITPIX 8 or 16 and NAXIS 2 are
|
|
supported. Both DSS PLATE headers and the traditional World
|
|
Coordinate System fields (CTYPE, CROTA, CRPIX, CDELT and CRVAL, 1 and
|
|
2) are supported. BSCALE and BZERO are not supported at this time.<br>
|
|
<br>
|
|
<span style="font-style: italic;">Note:</span> XEphem treats the 16
|
|
bit pixels as unsigned values from 0 through 65535, unlike the
|
|
standard which specifies they be treated as signed with values from
|
|
-32768 through 32767. XEphem assigns the coordinate [0,0] to be the
|
|
center of the first pixel in the file, unlike the standard which
|
|
specifies this position be at coordinate [1,1].<br>
|
|
</div>
|
|
<span style="font-weight: bold;"></span><br>
|
|
<span style="font-weight: bold;">Save as:</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> The image currently displayed, if any,
|
|
may be saved to disk as a FITS file. The file name is specified in
|
|
the text field provided. If <span style="font-weight: bold;">Auto
|
|
name</span> is turned on, a filename is automatically created derived
|
|
from the RA and Dec of the center of the image. An attempt is made to
|
|
preserve any existing directory and filename extensions, such that
|
|
the filename is constructed between the right-most '/' and the
|
|
right-most '.' characters, if possible. You may also type in your
|
|
own name.<br>
|
|
<br>
|
|
When an image is saved, its current contrast settings are added to
|
|
the FITS headers. If these fields are present when the file is
|
|
opened these settings will automatically be put back into effect.
|
|
See <a href="#SkyIP_Contrast">Contrast</a>.<br>
|
|
</div>
|
|
<br>
|
|
<span style="font-weight: bold;"></span><span style="font-weight: bold;">File
|
|
watch:</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This feature allows XEphem to
|
|
automatically discover and display FITS files that were created by
|
|
another program. When <span style="font-weight: bold;">Watch</span> is
|
|
turned on, XEphem will try to open the <span
|
|
style="font-style: italic;">watch</span>
|
|
file named in the text field provided here approximately once each
|
|
second and display the file named on the first line of the <span
|
|
style="font-style: italic;">watch</span> file. If successful XEphem
|
|
removes the <span style="font-style: italic;">watch</span> file as a
|
|
means to handshake the image has been displayed.<br>
|
|
<br>
|
|
With this feature and the popularity of various networked file systems
|
|
(NFS, Samba, etc) it is quite reasonable to display images with
|
|
XEphem that were captured on an entirely different computer, or on
|
|
the same computer running camera control software unrelated to
|
|
XEphem.<br>
|
|
<br>
|
|
A further note to implementors: XEphem also supports the <span
|
|
style="font-style: italic;">watch</span> file being a fifo. In this
|
|
case, XEphem will open the fifo and block trying to read a path name up
|
|
to the first newline. There is no handshake in this case. The fifo
|
|
approach is actually a bit more efficient than the file approach
|
|
because no polling is required. </div>
|
|
<br>
|
|
<a name="SkyIP"></a>
|
|
<h3><a class="mozTocH1" name="mozTocId883609"></a> 5.6.2 Image Analysis Tools</h3>
|
|
The Sky Image Tools window offers several functions with which to
|
|
analyze the FITS file showing in the Sky View. There are a few sample
|
|
FITS files included with which to practice using the tools.<br>
|
|
<br>
|
|
The window is divided into several separate sections, each of which
|
|
can be opened and closed as desired. Always present at the top of the
|
|
window is a block of basic information about the image. The statistics
|
|
ignore a border of 8 pixels. The information shown is: file name;
|
|
width and height; value and location of brightest pixel; value of
|
|
dimmest pixel; mean, median and standard deviation of all pixels.<br>
|
|
<br>
|
|
Note two <span style="font-style: italic;">important differences</span>
|
|
between XEphem and FITS: 1) XEphem treats the 16 bit image pixels as
|
|
unsigned values from 0 through 65535, unlike the FITS standard which
|
|
specifies they be treated as signed with values from -32768 through
|
|
32767. 2) XEphem image coordinates are one less than the FITS
|
|
standard. FITS defines the center of the first pixel in the file to be
|
|
at [1,1] while XEphem defines it to be at [0,0]. <a
|
|
name="SkyIP_Contrast"></a>
|
|
<h4><a class="mozTocH1" name="mozTocId410584"></a> 5.6.2.1 Brightness and
|
|
Contrast</h4>
|
|
<img style="width: 230px; height: 372px;" alt="" title=""
|
|
src="png/sky-images-ia-contrast.png" align="right" hspace="20">This
|
|
section controls the mapping between image pixels and screen colors.
|
|
It does not modify image pixels in any way.<br>
|
|
<br>
|
|
<img style="width: 30px; height: 27px;" alt="" title=""
|
|
src="png/sky-images-ia-contrast-tb.png" align="left">This section may
|
|
also
|
|
be opened using the button in the left Sky View toolbar that looks like
|
|
a circle filled with black on the right half.<br>
|
|
<br>
|
|
The top nine buttons offer shortcuts to set or adjust the image
|
|
appearance according to predefined algorithms.<br>
|
|
<br>
|
|
<span style="font-weight: bold;">Reverse</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> toggles between assigning brightness
|
|
in
|
|
direct or inverse proportion to image pixel values. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Narrow</span>, <span
|
|
style="font-weight: bold;">Wide</span> and <span
|
|
style="font-weight: bold;">Full</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> correspond to high, medium and low
|
|
contrast settings. These are implemented using increasingly broader
|
|
assignments of brightness about the mean pixel value in the image.
|
|
Narrow assigns full black and white to the mean ± 1/3 Std Dev.
|
|
Wide assigns black to mean - 1*StdDev and white to mean + 2*StdDev.
|
|
Full
|
|
assigns black to the smallest pixel and white to the largest pixel
|
|
in the entire image. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Sharper</span> and <span
|
|
style="font-weight: bold;">Duller</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> change contrast by changing the slope
|
|
of the pixel-to-brightness map to be steeper or flatter. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Brighter</span> and <span
|
|
style="font-weight: bold;">Darker</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> change the brightness by shifting the
|
|
center of the pixel-to-brightness map to higher or lower pixel
|
|
values. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Nominal</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> ignores the statistical distribution
|
|
of
|
|
pixel values and sets the map entirely on the basis of the minimum
|
|
and maximum pixel. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Low</span> and <span
|
|
style="font-weight: bold;">Hi</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> are text fields in which one may type
|
|
(or paste) the exact pixel values to be assigned to black and white.
|
|
A new value takes effect when Enter is pressed. These fields also
|
|
always show the current settings installed by any of the shortcuts. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Gammas</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> is set using the scale just above the
|
|
graph. The mapping from pixels to display colors is a power
|
|
function. Values of gamma less than 1 emphasize dark pixels, gamma
|
|
values greater than 1 emphasize bright pixels. </div>
|
|
<br>
|
|
The <span style="font-weight: bold;">graph</span> contains two
|
|
overlaid
|
|
plots. The horizontal axis for each plot is the same: the full range
|
|
of pixel values within the image, with lowest on the left. The <span
|
|
style="font-weight: bold;">orange line</span> is a histogram of the
|
|
number of pixels with each value. The <span style="font-weight: bold;">yellow
|
|
line</span> indicates the brightness at which each pixel value will be
|
|
displayed on the screen. You may control the black and white limits of
|
|
the mapping function from the graph by dragging the <span
|
|
style="font-weight: bold;">red arrows</span> at the top of the
|
|
diagram.
|
|
You may control gamma by sliding the scale ust above the graph.<br>
|
|
<br>
|
|
When XEphem saves an image, it adds three fields to the FITS header
|
|
to save the current contrast settings. When it loads an image, if
|
|
these fields are present they are used to restore the same display
|
|
contrast. If these fields are not present, the Wide setting is used.
|
|
These fields are: XELOGLUT: the pixel value assigned to black
|
|
XEHIGLUT: the pixel value assigned to white XEGAMMA: the value of
|
|
Gamma. <a name="SkyIP_Slice"></a>
|
|
<h4><a class="mozTocH1" name="mozTocId203653"></a> 5.6.2.2 Cross section Slice</h4>
|
|
<img alt="" src="png/sky-images-ia-slice.png" align="right" height="348"
|
|
hspace="10" vspace="10" width="232">Opening
|
|
this section lets you use the mouse to drag a line across the image
|
|
and display the pixels along that line. The graph is labeled
|
|
vertically in pixel value, horizontally as pixel distance from the
|
|
starting point. The line begins where the left mouse button
|
|
is first depressed.<br>
|
|
<br>
|
|
<blockquote><b>Full pixel range</b> toggle when set scales the vertical
|
|
scale to the full range of pixel values in the image, else scales to
|
|
the pixel range from Lo to Hi as defined in the
|
|
Brightness and Contrast section.<br>
|
|
</blockquote>
|
|
<br>
|
|
<img style="width: 32px; height: 30px;" alt="" title=""
|
|
src="png/sky-images-ia-slice-tb.png" align="left">This section may
|
|
also
|
|
be opened using the button in the right Sky View toolbar that looks
|
|
like a slice of bread.<br clear="all">
|
|
<a name="SkyIP_Glass"></a>
|
|
<h4><a class="mozTocH1" name="mozTocId408614"></a> 5.6.2.3 Magnifying Glass</h4>
|
|
<img style="width: 230px; height: 577px;" alt="" title=""
|
|
src="png/sky-images-ia-glass.png" align="right" hspace="20">This
|
|
section gives control over and shows information about the pixels in
|
|
the magnifying glass.<br>
|
|
<br>
|
|
Click and hold the left mouse button as you roam over the image and
|
|
you will see an expanded view of the pixels. The <span
|
|
style="font-weight: bold;">Size</span> and <span
|
|
style="font-weight: bold;">Mag</span>nifying power of the glass can be
|
|
set as desired using the two rows of toggle buttons. Note the numbers
|
|
on these buttons are in units of screen pixels, not image pixels. So
|
|
for example if you zoom in on an area the magnifying glass will expand
|
|
it correspondingly further.<br>
|
|
<br>
|
|
<img style="width: 32px; height: 29px;" alt="" title=""
|
|
src="png/sky-images-ia-snap-tb.png" align="left">While roaming you
|
|
might want to turn on the Jump to Max button on the right hand toolbar.
|
|
It is the one with the bright dot in the center to which a meandering
|
|
arrow finally points. When this button is on, XEphem will begin at the
|
|
pixel under the real cursor and walk the gradient to the brightest
|
|
connected pixel. All processing proceeds as though this brightest
|
|
pixel is where the cursor really pointed.<br>
|
|
<br>
|
|
Statistics about the image pixels under the glass are shown in the
|
|
table. All values are in pixels, all locations are in image
|
|
coordinates.
|
|
Fractional image coordinates occur because the image is resized to fit
|
|
the window which results in rational values for the scale factors. If
|
|
you zoom in enough to clearly see individual image pixels, you can see
|
|
that the coordinate system for image pixels puts the integral position
|
|
in the center.<br>
|
|
<br>
|
|
The statistics in the table include:<br>
|
|
<div style="margin-left: 40px;">
|
|
<ul>
|
|
<li>Size of the area under the glass;</li>
|
|
<li>Value and location of the center;</li>
|
|
<li>Value and location of the largest pixel under the glass;</li>
|
|
<li>Value of the minimum pixel;</li>
|
|
<li>Mean value of all glass pixels;</li>
|
|
<li>Median value of all glass pixels;</li>
|
|
<li>One Standard Deviation of the pixel values about the mean.</li>
|
|
</ul>
|
|
</div>
|
|
<br>
|
|
Below the statistics box you can optionally open windows that plot
|
|
the row or column through the center of the glass. The horizontal axis
|
|
of each graph is in image pixels, the vertical is in image pixel
|
|
values.<br>
|
|
<br>
|
|
<img style="width: 32px; height: 27px;" alt="" title=""
|
|
src="png/sky-images-ia-glass-tb.png" align="left">This section may
|
|
also
|
|
be opened using the button in the right Sky View toolbar that looks
|
|
like a box containing a few stars much larger than the others.
|
|
However, since the glass is useful in its own right, the toolbar
|
|
button only opens this section if the Image Tools window is already
|
|
up. Similarly, closing this section does not also turn off the toolbar
|
|
button.<br clear="all">
|
|
<a name="SkyIP_ROI"></a>
|
|
<h4><a class="mozTocH1" name="mozTocId487105"></a> 5.6.2.4 Region of Interest</h4>
|
|
<img style="width: 230px; height: 266px;" alt="" title=""
|
|
src="png/sky-images-ia-roi.png" align="right" hspace="20">This
|
|
section lets you use the mouse to draw a rectangle over the image and
|
|
get statistics about the pixels within this region. The area is the
|
|
same as that which can be used to specify a region in which to zoom.<br>
|
|
<br>
|
|
<img style="width: 30px; height: 29px;" alt="" title=""
|
|
src="png/sky-images-ia-roi-tb.png" align="left">This section may also
|
|
be opened by the right toolbar button that looks like a boxdrawn around
|
|
a galaxy.<br>
|
|
<br>
|
|
The following statistics about the image pixels in the ROI are shown
|
|
in the table:<br>
|
|
<ul>
|
|
<li>Length of the diagonal;</li>
|
|
<li>Width and height of the region;</li>
|
|
<li>Value and location of the cursor as you draw the ROI;</li>
|
|
<li>Value and location of the largest pixel in the ROI;</li>
|
|
<li>Value of the minimum pixel;</li>
|
|
<li>Mean value of all ROI pixels;</li>
|
|
<li>Median value of all ROI pixels;</li>
|
|
<li>One Standard Deviation of the pixel values about the mean.</li>
|
|
</ul>
|
|
<br clear="all">
|
|
<br clear="all">
|
|
<br>
|
|
<a name="SkyIP_2D_Gaussian"></a>
|
|
<h4><a class="mozTocH1" name="mozTocId800569"></a> 5.6.2.5 2D Gaussian
|
|
Measurements</h4>
|
|
<img style="width: 240px; height: 283px;" alt="" title=""
|
|
src="png/sky-images-ia-gauss.png" align="right" hspace="20">This
|
|
section is based on results of modeling stars with a 2 dimensional
|
|
Gaussian.<br>
|
|
<br>
|
|
The model finds the coefficients in the following function of pixel
|
|
coordinates x and y that minimizes the Chi square error with each
|
|
pixel in an area:<br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> <span style="font-family: monospace;">g(x,y)
|
|
= B + A*exp(-0.5*(sqr((x-mx)/sx) + sqr((y-my)/sy)))</span> </div>
|
|
<br>
|
|
where<br>
|
|
<div style="margin-left: 40px;"> mx is the row coordinate from some
|
|
reference position,<br>
|
|
my is the same for a column,<br>
|
|
sx is the standard deviation of the pixel values along a row,<br>
|
|
sy is the same for a column,<br>
|
|
A is the peak height of function ( = g(xm,ym) - g(inf,inf)),<br>
|
|
B is the mean of the row and column pixels. </div>
|
|
<br>
|
|
[mx,my] is then taken to be the location of the star, the volume as
|
|
proportional to A*sx*sy as a measure of its magnitude, and B a measure
|
|
of the mean noise level of the surrounding pixels.<br>
|
|
<br>
|
|
In practice, we find this method converges quickly and yields
|
|
positional results accurate to .2 pixel or so. Magnitudes and their
|
|
error estimates depend strongly on whether the image was ever
|
|
compressed, proper image correction, linearity of ADU counts with
|
|
brightness, and other factors. When these factors are properly
|
|
addressed, magnitude ratios seem to be good to .02 mag or so over
|
|
differences of several magnitudes.<br>
|
|
<br>
|
|
The text box shows the results of this fitting process on the image
|
|
pixels that are centered on the cursor and lie within the area defined
|
|
by the magnifying glass settings (whether or not the glass is actually
|
|
turned on). The numbers report the following:<br>
|
|
<ul>
|
|
<li>Relative magnitude difference and error estimate between the
|
|
current star and the reference star;</li>
|
|
<li>Position of the star, in image coordinates and in RA/Dec if WCS
|
|
header fields are present;</li>
|
|
<li>Full-width-half-max of the star in each dimension in pixels,
|
|
and in arc seconds if the image scale is known from header fields
|
|
CDELT1 and CDELT2;</li>
|
|
<li>The pixel value representative of the noise level base in the
|
|
area (B in the above equation);</li>
|
|
<li>The pixel value of the peak of the Gaussian fit (A+B in the
|
|
equation).</li>
|
|
</ul>
|
|
If there is a number in the <span style="font-weight: bold;">Reference
|
|
Mag</span> text field, it is simply added to the magnitude reported.
|
|
The idea is to set this to the magnitude of a star (known by
|
|
independent means) and use that star as the reference for subsequent
|
|
comparison. Since the reference is now calibrated, magnitudes reported
|
|
will be absolute not just relative. Except under special situations,
|
|
the reference star will not be applicable to other images, although
|
|
XEphem does not prevent you from doing this.<br>
|
|
<br>
|
|
The reference star can be established in several ways.<br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> One way is automatic in the sense that
|
|
if there is no current reference, the first star that is measured is
|
|
also automatically given the role as reference for subsequent
|
|
comparisons. </div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> After any star has been measured, it
|
|
can be made the reference by clicking on <span
|
|
style="font-weight: bold;">New.</span> Clicking <span
|
|
style="font-weight: bold;">Mark</span> will draw a small circle in
|
|
the image around the current reference star in case you lose track
|
|
of it. </div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Another way to set the reference is to
|
|
use a catalog star. This is only possible, of course, if the header
|
|
includes WCS coordinates. Right-click on the catalog star in the Sky
|
|
View and choose the entry <span style="font-weight: bold;">New Photom
|
|
ref</span>. This will perform the Gaussian fit on the pixels at
|
|
that stars location in the image, and assign the Reference Magnitude
|
|
to the catalog value. </div>
|
|
<br>
|
|
<img style="width: 30px; height: 27px;" alt="" title=""
|
|
src="png/sky-images-ia-gauss-tb.png" align="left">This section of the
|
|
Sky image tools window can be opened by clicking on the button in the
|
|
right toolbar that looks like a Gaussian graph (or perhaps a large
|
|
nose).<br>
|
|
<br>
|
|
<img style="width: 32px; height: 29px;" alt="" title=""
|
|
src="png/sky-images-ia-snap-tb.png" align="left">While measuring stars
|
|
you might want to turn on the Jump to Max button on the right hand
|
|
toolbar too. It is the one with the bright dot in the center to which
|
|
a meandering arrow finally points. When this button is on, XEphem will
|
|
begin at the pixel under the real cursor and walk the gradient to the
|
|
brightest connected pixel. All processing proceeds as though this
|
|
brightest pixel is where the cursor really pointed.<br>
|
|
<h3><a class="mozTocH4" name="mozTocId941910"></a> 5.6.3 <a name="imreg"></a><img
|
|
alt="" src="png/imreg.png" align="right" height="188" hspace="5"
|
|
vspace="5" width="300">Registration<br>
|
|
</h3>
|
|
This window lets you register, or align, one or more images to a
|
|
reference image. The motivation for this feature is to make a
|
|
movie of a moving object that has been captured in several images.
|
|
Load the reference image into a new <a href="#Movie">Movie</a> then
|
|
load each additional image after it is aligned.<br>
|
|
<br>
|
|
The alignment algorithm requires two stars that appear in each image.
|
|
Using two stars is the most general method of defining a 2D coordinate
|
|
system and is used for its robust performance. It is possible to use
|
|
just one star, but the technique requires the software to make
|
|
assumptions about matching features in the image. We feel the slightly
|
|
larger burden of defining two stars is worth the results. When choosing
|
|
the two reference stars, select stars that are well separated in both
|
|
rows
|
|
and columns, isolated from neighboring stars, moderately bright and
|
|
well
|
|
formed.<br>
|
|
<br>
|
|
To begin, load the reference image into Sky View and adjust the
|
|
contrast or other visual effects as desired. Then click the first
|
|
toggle in the window. The cursor will change over the Sky View to a
|
|
small cross. Place the cursor over one reference star and click; you
|
|
will see the Gaussian centroid image coordinates of the star
|
|
appear in the registration window for Star 1. Now choose a second
|
|
reference star and click again. You will see its coordinates appear for
|
|
Star 2, the cursor will revert back to the original style and the
|
|
toggle button will pop back out. If you ever want to change the
|
|
reference image choose different reference stars, you can turn on the
|
|
top
|
|
toggle again at any time and restart the procedure. This is a good time
|
|
to
|
|
delete any frames currently in the Movie tool and add the reference
|
|
image to form the first frame of a movie.
|
|
<br>
|
|
<br>
|
|
Now you can load a second image. Again, adjust contrast and so on as
|
|
desired. Click on the second toggle in the registration window and
|
|
proceed as before to click on <i>the same two stars</i> in the second
|
|
image. Be sure to click on the two stars in the same order, so that the
|
|
first star clicked when defining the reference stars is also the first
|
|
star clicked when working on the second image.<br>
|
|
<br>
|
|
As soon as the second star is clicked on the second image, the image
|
|
will be transformed using translation, scaling and rotation in such a
|
|
way as to align the two stars with their location in the reference
|
|
image. The contrast settings are preserved for you even though the
|
|
image
|
|
pixel statistics have changed due to the addition of new black pixels
|
|
where
|
|
the images do not overlap and the loss of pixels that do not fit over
|
|
the
|
|
reference image. If the results look useful, add it to the Movie.<br>
|
|
<br>
|
|
You may repeat the process of aligning additional images with the
|
|
reference image for as many images you like.<br>
|
|
<br>
|
|
Note that while either toggle is turned on in the registration window,
|
|
the other image analysis tools are temporarily disabled. Note also that
|
|
the algorithm used to transform the image to match the reference image
|
|
is
|
|
designed primarily for speed. The stars in the transformed image are a
|
|
little
|
|
distorted and we recommend you not use these images for precise
|
|
photometry or
|
|
astrometry.<br>
|
|
<br>
|
|
<a name="SkyIP_WCS"></a>
|
|
<h3><a class="mozTocH1" name="mozTocId771440"></a> 5.6.4 WCS Solver</h3>
|
|
<img alt="" src="png/wcssolver.png" align="right" height="187"
|
|
hspace="10" width="413">This window controls a pattern matching
|
|
algorithm that attempts to
|
|
register the star-like artifacts in a FITS image with the entries in
|
|
any or all of the XEphem Field Star catalogs. See <a
|
|
href="#Field_Stars_">Field stars</a>.<br>
|
|
<b><br>
|
|
</b>The solver will be invoked automatically whenever a FITS file is
|
|
loaded whose header includes all the seed fields but does not already
|
|
have a WCS solution.<br>
|
|
<tt></tt><br>
|
|
<tt><br>
|
|
</tt>
|
|
<div style="margin-left: 40px;"> <span style="font-weight: bold;">Rows
|
|
1-5: setting seed values</span> </div>
|
|
<br>
|
|
<div style="margin-left: 80px;"> The first five rows seed the search
|
|
with approximate coordinates for the center of the image, the scale
|
|
of the image pixels in each direction, and a possible rotation. The
|
|
center must be known to within about one half the smaller of the image
|
|
width and height. The scale must be known to within about 10%. The
|
|
rotation seed need not be accurate at all, but better estimates will
|
|
result in vastly faster solution times. Indeed, better values for any
|
|
field will improve the solution speed and also reduce the chances of a
|
|
false solution. </div>
|
|
<br>
|
|
<div style="margin-left: 80px;"> Each of the fields may be typed or
|
|
pasted into the fields down the left. But often FITS files will
|
|
include fields which contain information suitable for this purpose.
|
|
In the column down the right you may enter the names of such fields.
|
|
Clicking the <span style="font-weight: bold;">Use field</span> button
|
|
in
|
|
a row will read the value from the header field named on the right and
|
|
install it into the field on the left of the same row, possibly after
|
|
some reformatting and change of units. Certainly not all forms are
|
|
supported so please take care to check for proper units and
|
|
formatting yourself. The default fields supplied are fairly common
|
|
and are known to work if you are lucky enough to have them in your
|
|
images. </div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> <span style="font-weight: bold;">Row
|
|
6: scanning the image for star-like artifacts</span> </div>
|
|
<br>
|
|
<div style="margin-left: 80px;"> The next row contains two parameters
|
|
which control the algorithm that scans an image to extract what seem
|
|
to be reasonable candidates for stars, that presumably will also be
|
|
in a Field star catalog. </div>
|
|
<br>
|
|
<div style="margin-left: 80px;"> <span style="font-weight: bold;">Burned
|
|
out</span>: This parameter sets the largest pixel value (in the
|
|
range 0 .. 65535) a star may contain. Groups of pixels being
|
|
considered as a candidate star by the algorithm will immediately
|
|
reject the entire group if even one pixel is higher than this. The
|
|
idea here is that if a star is so bright as to be even a little burned
|
|
out, its centroided position is likely to be worse than not using it
|
|
at all. If you feel otherwise, set this to 65535 and no groups will
|
|
be rejected (at least for this reason). </div>
|
|
<br>
|
|
<div style="margin-left: 80px;"> <span style="font-weight: bold;">S/N
|
|
ratio</span>: This parameter sets the minimum signal-to-noise ratio
|
|
of a candidate star. The algorithm breaks an image into several
|
|
smaller regions and computes several statistics of all the pixels in
|
|
that region. In order for a group of pixels to be considered a star,
|
|
its
|
|
brightest pixel must be at least the median plus this parameter
|
|
multiplied by the standard deviation computed from the statistics of
|
|
the region in which it is located. Basically, the larger this
|
|
number, the more distinct the star must be. </div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> <span style="font-weight: bold;">Row
|
|
7: Setting realistic search goals</span> </div>
|
|
<br>
|
|
<div style="margin-left: 80px;"> The bottom row contains two parameters
|
|
that effect the goal of the search algorithm.<br>
|
|
<br>
|
|
<span style="font-weight: bold;">Max pix acc</span>: This parameter
|
|
tells the search algorithm not to expect position information for
|
|
the star-like artifacts extracted from an image to be any better
|
|
than this fraction of a pixel.<br>
|
|
<br>
|
|
<span style="font-weight: bold;">Min pix acc</span>: This is the
|
|
worst pixel distance acceptable between each image star and its
|
|
closest catalog star. </div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> <span style="font-weight: bold;">Go</span>
|
|
</div>
|
|
<blockquote>
|
|
<blockquote>Commences the search for a solution
|
|
using the image currently in the Sky View and the parameters in
|
|
the various fields above. If a solution is found, each star used
|
|
in the solution will be circled and statistics about the quality
|
|
of the solution will be presented. The WCS fields that
|
|
characterize the solution are written into the FITS header. If you like
|
|
the solution, Save the
|
|
image and this solution will be saved with the image and searching
|
|
will not be needed next time. </blockquote>
|
|
</blockquote>
|
|
<blockquote><span style="font-weight: bold;">Mark stars</span><br>
|
|
</blockquote>
|
|
<blockquote>
|
|
<blockquote> Clicking this button will draw a small
|
|
circle around each group of pixels in the image the algorithm
|
|
considers to be a star. Use this to choose good values for Burned
|
|
out and S/N ratio.<br>
|
|
</blockquote>
|
|
</blockquote>
|
|
<b>WCS Solver Tutorial<br>
|
|
</b><br>
|
|
<blockquote>The first step is to supply suitable seeds values for the
|
|
center of the image, the image scale and any suspected rotation. If the
|
|
FITS image header contains fields with these values, enter the names of
|
|
the fields in the spaces provided and they will be extracted
|
|
automatically when the image is loaded. If the header does not contain
|
|
this information, or the units are not correct, then seed values must
|
|
be entered manually in the fields provided. Note that the pixel scale
|
|
values must have the correct sign since the algorithm automatically
|
|
takes into account rotation but not flipping.<br>
|
|
<br>
|
|
The second step is to set the SNR value so that Marking stars finds
|
|
most of the brightest and well-formed star-like objects in the image,
|
|
without also finding bogus star candidates. Also, if the image was over
|
|
exposed so that very bright stars are washed out, eliminate these by
|
|
reducing the value for burned out stars.<br>
|
|
<br>
|
|
Once good stars are being marked, the last step is to indicate how
|
|
accurately star centroids can be determined and how accurate any
|
|
solution is likely to be using the bottom two fields of the form.<br>
|
|
<br>
|
|
Another issue is to use an appropriate field star catalog. More
|
|
stars is not necessarily better. For example, the GSC 2.2
|
|
goes to mag 18 but also tends to have more bogus entries near very
|
|
bright stars. If your image contains a very bright star, take note of
|
|
the field stars that are near it; you might do better with the GSC 1.2
|
|
than 2.2 catalogs.<br>
|
|
<br>
|
|
After adjusting any field, click Go. If a solution is found, the stars
|
|
used in the fit will be marked and statistics about the fit will be
|
|
displayed.<br>
|
|
<br>
|
|
This algorithm has proven to be very robust over the years. With a
|
|
little practice it can usually be made to work quite well.<br>
|
|
</blockquote>
|
|
<span style="font-weight: bold;"><br>
|
|
</span>
|
|
<h2><a class="mozTocH3" name="mozTocId618558"></a> 5.7 <a
|
|
name="SkyView_favorites"></a> <a class="mozTocH1"
|
|
name="mozTocId101286"></a> Sky View Favorites
|
|
menu</h2>
|
|
This brings up a menu of the current Favorite objects. Clicking an
|
|
entry will place a cross-hair over the object and activate the same
|
|
<a href="#Sky_view_popup_right_button">popup menu</a>
|
|
that would appear if the object had been right-clicked over the map.
|
|
If the object is not
|
|
within the field of view the Sky View will be moved so the object is
|
|
centered. If Alt-Az mode is currently active and the object is below
|
|
the horizon, the view will not be changed and a message will suggest
|
|
the mode first be changed to RA-Dec.
|
|
Favorites may be managed from the <span
|
|
style="font-family: monospace;">Control » Favorites</span>
|
|
window. See <a href="#Favorites">Favorites</a>.<br>
|
|
<br>
|
|
<a name="SkyView_telescope"></a>
|
|
<h2><a class="mozTocH1" name="mozTocId365647"></a> 5.8 Sky View Telescope
|
|
menu</h2>
|
|
The Telescope menu in Sky View
|
|
allows you to connect to and control a telescope and, if using the INDI
|
|
protocol, any other instrumentation whatsoever. The control can be
|
|
performed via a simple fifo connection, or a much more flexible INDI
|
|
interface. For a complete description of the INDI protocol, please
|
|
download the reference specification from <a
|
|
href="http://www.clearskyinstitute.com/INDI/INDI.pdf">http://www.clearskyinstitute.com/INDI/INDI.pdf</a>.
|
|
Here we only describe the INDI configuration window, the INDI
|
|
control panel, testing the INDI system using the sample drivers, and
|
|
finally the simple fifo interface.<br>
|
|
<br>
|
|
Regardless of which means is used to send a new position to a
|
|
telescope, the menu contains a history list of targets. Clicking on one
|
|
of these will send that target again. A button is available to erase
|
|
the list at any time.<br>
|
|
<h3><a class="mozTocH4" name="mozTocId87479"></a> 5.8.1 INDI Test Drivers</h3>
|
|
Beneath the source directory of XEphem is a directory <tt>tools/indi</tt>.
|
|
This contains several sample INDI drivers that together simulate an
|
|
entire observatory. Please read the README and follow the instructions
|
|
to build and run the sample drivers. This will allow you to perform a
|
|
live test of XEphem's INDI windows to be described next.<br>
|
|
<h3><a class="mozTocH4" name="mozTocId620571"></a> 5.8.2 INDI Configuration
|
|
window</h3>
|
|
<img alt="" src="png/indiconfig.png" align="right" height="318"
|
|
width="674">The top row of this window contains two text fields by
|
|
which you to
|
|
specify the TCP/IP host and port name to which a connection is to be
|
|
made to an INDI driver or server. The default values are suitable for
|
|
running the test drivers mentioned above.<br>
|
|
<br>
|
|
The remaining rows define the mapping between internal XEphem
|
|
functionality and the external INDI devices. All information flows over
|
|
the INDI protocol based on Properties. Each property is defined as a
|
|
Device, a Property and an array of one or more Elements. The INDI
|
|
protocol does not
|
|
prescribe the names or the meanings of Properties, it is up to the
|
|
client and servers to agree. Recommended practice will evolve as
|
|
community participation matures. The sample drivers supplied with
|
|
XEphem make some possible choices for properties and names.<br>
|
|
<br>
|
|
The default settings in the Configuration window are the correct
|
|
mappings for these sample drivers. The idea is to specify the
|
|
Device.Property.Element that corresponds to each purpose. The
|
|
Configuration window also allows entering a multiplier and offset that
|
|
is applied to the INDI value to compute the value in units used within
|
|
XEphem. For example, the units for Mount.EQUATORIAL_COORD.RA are hours
|
|
but XEphem
|
|
wants this value in radians, hence the multiplier set to 0.2617993.
|
|
When connecting to drivers for which the
|
|
name mapping is not yet known, one technique for discovering their
|
|
Properties is to watch the INDI Control Panel (described next) for each
|
|
new Property that is reported when connecting toan INDI server. <br>
|
|
<br>
|
|
One of the options is whether to display a <b>marker</b> at the
|
|
telescope position on the Sky View. Below this ia a toggle button to
|
|
specify whether the Sky
|
|
View will automatically <b>Recenter</b> in order to keep the telescope
|
|
Marker in the
|
|
field of view. The option applies both to INDI and fifo marker
|
|
commands. When Recenter is On, then the telescope Marker is
|
|
automatically turned off whenever the Sky View is manually adjusted
|
|
(the rationale being that one will most likely not want the Sky View to
|
|
bounce back to the telescope position after having been manually
|
|
changed).<br>
|
|
<br>
|
|
Note that the sample drivers do not support all XEphem functionality.
|
|
For example, the sample drivers do not support being sent a new time
|
|
and date. This is included in XEphem in case it is useful someday for
|
|
some other driver and to illustrate how XEphem stores dates internally
|
|
as a modified Julian date, ie, with an offset of 2415020 removed.<br>
|
|
<h3><a class="mozTocH4" name="mozTocId249275"></a> 5.8.3 INDI Control Panel</h3>
|
|
<img alt="" src="png/indicontrol.png" align="right" height="432"
|
|
width="561">This window shows the realtime operation of an INDI
|
|
server. It is
|
|
divided into a top and bottom section. The proportion of screen space
|
|
used by each half may be controlled using the sash control located
|
|
just about the bottom scrolled area.<br>
|
|
<br>
|
|
The top half is a scrolled text area that shows the status messages
|
|
arriving from each device. Each message is preceded with a time stamp,
|
|
followed by the Device followed by the message text. The <b>Erase</b>
|
|
button will permanently remove all messages from the scrolled text.
|
|
Clicking on the <b>Trace to</b> button will append the current set of
|
|
messages to the file named in the text field to the right and append
|
|
all further messages to this file until tracing is turned off.<br>
|
|
<br>
|
|
The bottom half shows each INDI Device, Property and Element to which
|
|
XEphem is connected. Each Device may be expanded or collapsed to
|
|
control screen space. The entire list can be scrolled up and down. The <b>Connect</b>
|
|
button controls whether XEphem will connect to the INDI device whose
|
|
host and port are defined in the INDI Configuration window. If a
|
|
connection is successful, each of the reported Properties will appear
|
|
in the bottom scrolled area.<br>
|
|
<br>
|
|
Under each Device is a list of its Properties. Each INDI Property may
|
|
be in one of four states: Idle, Ok, Busy and Alert. These are shown as
|
|
a light to the left of the Property colored gray, green, yellow and
|
|
red, respectively. To the left of each Device is also a light, colored
|
|
the same the highest activity color of any of its Properties. In this
|
|
way the status of the most active Property can be determined even when
|
|
a Device is collapsed in the window.<br>
|
|
<br>
|
|
INDI Properties can be one of four types. These are Numeric, Text,
|
|
Switches and Lights. The first three may be read-write or read-only. A
|
|
light is always considered read-only (set only by the Device, not by
|
|
the operator). Each Element of each Property is shown on one line. The
|
|
left side of the line is the label. Following the label is the current
|
|
value and, if read-write, followed by a text field for entering a new
|
|
value. Read-write Properties will have a push button to the left of
|
|
their name to set a new value; pressing Return in the text field will
|
|
also set a new value. Switches will show each switch with their label.
|
|
Switches may be defined to operate according to the rules one-of-many,
|
|
any-of-many and at-most-one.<br>
|
|
<br>
|
|
<a name="SkyViewFifo"></a><br>
|
|
<h3><a class="mozTocH1" name="mozTocId572031"></a> 5.8.4 FIFO Control</h3>
|
|
Completely separate from the INDI interface, Sky View implements two
|
|
simple
|
|
fifos for communicating with a telescope control dæmon or other
|
|
processes or scripts. Each fifo must be in either the
|
|
<a href="file://help/xephem.html#SharedPrivateDirs">Private</a>
|
|
or
|
|
<a href="file://help/xephem.html#SharedPrivateDirs">Shared</a>
|
|
directory.
|
|
<ol>
|
|
<li><b>Inbound:</b> A marker may be placed on the Sky View by
|
|
writing a text string to the fifo named <b>fifos/xephem_in_fifo</b>.
|
|
The format allows for sending either equatorial or horizon coordinates.
|
|
To send an equatorial coordinate, the format is "<tt>RA:X Dec:Y</tt>",
|
|
where X
|
|
and Y are in radians at epoch 2000.0. To send a horizon coordinate, the
|
|
format
|
|
is "<tt>Alt:X Az:Y</tt>", where X and Y are in radians. The Sky View
|
|
center pointing position will be changed if necessary to make the
|
|
marker
|
|
visible. XEphem attempts to open this fifo each time the Sky View
|
|
window is
|
|
opened and closes it when the view is closed. <br>
|
|
<br>
|
|
</li>
|
|
<li><b>Outbound:</b> If a process has the fifo named <b>fifos/xephem_loc_fifo</b>
|
|
open for reading when the Sky View popup menu is activated, then the
|
|
menu will
|
|
offer a button to send the cursor position to this fifo. The format is
|
|
the
|
|
same as a line in .edb format. If it is not already open XEphem
|
|
attempts to
|
|
open this fifo each time the popup is activated, and leaves it open
|
|
until
|
|
writing to it fails. Each position sent to the fifo is added to the
|
|
Telescope history list.<br>
|
|
</li>
|
|
</ol>
|
|
<a name="SkyView_history"></a>
|
|
<h2><a class="mozTocH1" name="mozTocId572030"></a> 5.9 Sky View History menu</h2>
|
|
This is the Sky View History control window. All Sky View Options,
|
|
Filter settings and pointing values may be saved in a History entry to
|
|
make it easy to configure the same way again at a later time. The <b>Edit</b>
|
|
pushbutton in the History pulldown menu brings up this window. The
|
|
additional pushbuttons in the History pulldown menu correspond to each
|
|
defined History entry and make it easy to apply any one history entry
|
|
without opening the History control window.<br>
|
|
<br>
|
|
The control window shows the current set of History entries, one per
|
|
line. The left portion of each line contains several controls,
|
|
described below. The center portion summarizes the entry, showing the
|
|
display mode, coordinate system, center position and field of view. The
|
|
right portion provides a text field to give the entry a name. This is
|
|
the name which appears in the History pulldown menu.<br>
|
|
<div style="text-align: center;"> <img
|
|
style="width: 581px; height: 193px;" alt="" title=""
|
|
src="png/sky-history.png" vspace="10"> </div>
|
|
<br clear="all">
|
|
The controls for each History entry are as follows:<br>
|
|
<br>
|
|
<blockquote><span style="font-weight: bold;">Apply</span><br>
|
|
<blockquote>puts the entry into effect, in the
|
|
same way as choosing it from the pulldown menu.<span
|
|
style="font-weight: bold;"><br>
|
|
</span></blockquote>
|
|
<span style="font-weight: bold;">Up</span><br
|
|
style="font-weight: bold;">
|
|
<span style="font-weight: bold;">Down</span><br>
|
|
<blockquote>moves the entry up or down in the list. <br>
|
|
</blockquote>
|
|
<span style="font-weight: bold;">Delete</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> removes the given entry. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Replace</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;">replaces the entry with the current
|
|
Sky View settings. </div>
|
|
</blockquote>
|
|
<br>
|
|
The buttons across the bottom allow for
|
|
additional control of the History list as a whole:<br>
|
|
<br>
|
|
<blockquote><span style="font-weight: bold;">Add</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> captures the current Sky View
|
|
settings
|
|
and creates a new History entry. A default name will be created but
|
|
you should probably change it to something more descriptive if you
|
|
plan to Save the list. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Save</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> writes all of the current History
|
|
entries to a file. The file name is <span style="font-weight: bold;">xephem_skyhist</span>
|
|
and will be created in the <a href="#SharedPrivateDirs">Private</a>
|
|
directory. You really don't want to know the format of this file. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Load</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> reads an existing file of History
|
|
entries that has been previously Saved and makes them the current
|
|
set. </div>
|
|
</blockquote>
|
|
<h2><a class="mozTocH3" name="mozTocId535793"></a> 5.10 <a
|
|
name="SkyView_binary"></a>Sky View Binary Star Map</h2>
|
|
<img alt="" src="png/sky-binary.png" align="right" height="278"
|
|
hspace="10" vspace="10" width="458">This window displays a map of a
|
|
binary
|
|
star system and a matching ephemeris. It is displayed from the popup
|
|
that appears when the mouse is right-clicked over a binary object in
|
|
the Sky View.<br>
|
|
<br>
|
|
The map is at left, oriented with equatorial N up and E left, as on the
|
|
unaided sky. Each star is drawn in a color according to its spectral
|
|
class. The primary star is drawn at the center. A scale at the bottom
|
|
shows the sky dimensions of the plot.<br>
|
|
<br>
|
|
If complete orbital elements are available, one orbit is plotted at
|
|
equal time intervals marked by small dots. The largest dot in the orbit
|
|
marks the position of the secondary nearest to the current XEphem time,
|
|
medium size dots mark other locations each ten steps.<br>
|
|
<br>
|
|
If only discrete positions for the secondary are known, the plot is
|
|
simply one dot for each.<br>
|
|
<br>
|
|
The table on the right lists the position of each plotted secondary
|
|
position. The columns are the dot number, year, separation in arc
|
|
seconds and
|
|
position
|
|
angle as degrees East of North. The separation and position angle at
|
|
the current XEphem time are available in the <i>More info</i> <a
|
|
href="#Sky_view_popup_right_button">pull-right</a> menu in the Sky
|
|
View popup.<br>
|
|
<br>
|
|
The <b>Print</b> button will print the map and the list.<br>
|
|
<br clear="all">
|
|
<br>
|
|
<h1><a class="mozTocH1" name="mozTocId255075"></a> 6.0 <span
|
|
style="font-weight: bold;">Tools menu</span></h1>
|
|
The tools menu provides access to a variety of functions.<br>
|
|
<br clear="all">
|
|
<a name="Plot"></a>
|
|
<h2><a class="mozTocH1" name="mozTocId138961"></a> 6.1 Plot values</h2>
|
|
<img style="width: 267px; height: 228px;" alt="" title=""
|
|
src="png/plot.png" align="right" hspace="10" vspace="10">
|
|
This window controls the plot generation and display
|
|
functionality of XEphem. You may select most numeric information
|
|
displayed throughout XEphem, in pairs, to form x/y coordinates of a
|
|
plot. You may select up to 40 such pairs. You then specify a file in
|
|
which to write the plot information. XEphem adds one line of
|
|
information
|
|
to the file for each x/y pair each Update iteration step. XEphem can
|
|
then plot any such file on the screen.<br>
|
|
<br>
|
|
<span style="font-weight: bold;">Selecting data to plot</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Click the toggle labeled <span
|
|
style="font-weight: bold;">Select fields to plot</span> to make each
|
|
field in the other windows that are eligible for plotting appear as
|
|
a pushbutton. Select each such button as desired to form the x or y
|
|
component of a plot. As you make the selections, they are listed in
|
|
the table. Use the <span style="font-weight: bold;">Undo</span> button
|
|
to make changes. You may also associate a tag with each line, up to 8
|
|
characters in length. These tags will be included in the plot display
|
|
for identification later. Once all the field choices have been made you
|
|
may return all the windows to their normal operational appearance by
|
|
deselecting the same toggle button.<br>
|
|
<br>
|
|
</div>
|
|
<span style="font-weight: bold;"><span style="font-weight: bold;">Saving
|
|
and restoring a plot configuration<br>
|
|
<br>
|
|
</span></span>
|
|
<div style="margin-left: 40px;"> To save this configuration so it can
|
|
be
|
|
loaded later, specify a file name and click <span
|
|
style="font-weight: bold;">Save config file</span>. It will be saved
|
|
in the <a href="#SharedPrivateDirs">Private</a> directory. The plot
|
|
entries will be savde in addition to the plot title field. The
|
|
extension for plot configuration files must be <span
|
|
style="font-weight: bold;">.ptc</span> and will be added automatically
|
|
if left off. A configuration file may be
|
|
loaded by selecting it from the option popup menu to the right of <span
|
|
style="font-weight: bold;">Load config file</span>. The menu will list
|
|
all files that reside in the Shared and Private directories with
|
|
extension .ptc. Note that reloading a configuration only recreates the
|
|
Plot's tag, x and y description; to be useful, the fields to which the
|
|
reloaded configuration refers must be made active independently.<br>
|
|
</div>
|
|
<span style="font-weight: bold;"><span style="font-weight: bold;"></span><br>
|
|
Specifying the plot file name and title</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Type the name of the file to be used
|
|
to
|
|
contain the plot information in the text field provided. The
|
|
extension must be <span style="font-weight: bold;">.plt</span> and
|
|
will be added automatically if left off. When
|
|
XEphem first needs to write to the file, it will first check for the
|
|
existence of the file and, if it already exists and the
|
|
Confirmations <a href="#MainMenu_preferences">Preferences</a> is On,
|
|
ask
|
|
whether you wish to append to the file or overwrite it.<br>
|
|
<br>
|
|
</div>
|
|
<div style="margin-left: 40px;"> Enter a short <span
|
|
style="font-weight: bold;">title</span> for the plot information in
|
|
the
|
|
text field provided. When XEphem first writes to a plot file, it
|
|
will place the contents of the title text field, if it is not empty,
|
|
into the file as a comment. All lines within a plot file that do not
|
|
begin with an alphanumeric character are considered comments and are
|
|
ignored. If the first line of a file is a comment, XEphem will use
|
|
it as the title when it displays the plot.<img
|
|
style="width: 236px; height: 251px;" alt="" title=""
|
|
src="png/plot-sample.png" align="right" hspace="10" vspace="10"><br>
|
|
<br>
|
|
</div>
|
|
<span style="font-weight: bold;">Generating the plot entries<br>
|
|
<br>
|
|
</span>
|
|
<div style="margin-left: 40px;"> Once the fields have been specified
|
|
and
|
|
the plot file named and titled, you may select the <span
|
|
style="font-weight: bold;">Create plot file</span> toggle button when
|
|
ready. Now each time XEphem goes through one Update iteration the
|
|
values
|
|
you have selected and their tags will be written to the plot file.
|
|
Note that when plotting is activated, XEphem does not update the
|
|
screen until the N Steps count in the Main window <a
|
|
href="#main_looping">looping</a> section goes to 1. This greatly
|
|
speeds the creation of plot files by avoiding screen updates. If you
|
|
wish to watch each iteration, set N Steps to 1 and click the Update
|
|
button manually for each iteration.<br>
|
|
<br>
|
|
Once all the desired data has been entered into the plot file, toggle
|
|
the plot button back off to flush all data and close the file. The
|
|
windows that contain each of the fields used in the plot need not be
|
|
visible while the plot is being generated. However, each field must
|
|
be active, for example its row and column must be selected if they
|
|
are in the Data table.<br>
|
|
<br>
|
|
</div>
|
|
<span style="font-weight: bold;">Viewing plot files<br>
|
|
<br>
|
|
</span>
|
|
<div style="margin-left: 40px;"> Existing plot files may be viewed by
|
|
choosing it in the menu to the right of <span
|
|
style="font-weight: bold;">Show
|
|
plot file</span>. The menu will list all files that reside in the
|
|
Shared and Private directories with extension .plt. As many different
|
|
plot files may be viewed simultaneously as desired. Each plot has
|
|
separate controls for flipping the X and Y axes and for turning on
|
|
and off a reference coordinate grid. The position under the cursor is
|
|
displayed above the top of the plot. The XEphem distribution kit
|
|
includes a sample plot file of the analemma.<br>
|
|
<br>
|
|
</div>
|
|
<br>
|
|
<a name="Listing"></a>
|
|
<h2><a class="mozTocH1" name="mozTocId310002"></a> 6.2 List values</h2>
|
|
<img alt="" title="" src="png/listing.png" align="right" height="241"
|
|
hspace="10" vspace="10" width="327"> This window controls the
|
|
list generation functionality of XEphem. The fields you select define
|
|
columns of a table written to a file as XEphem runs. The text in
|
|
these columns looks exactly like their corresponding fields on the
|
|
XEphem windows and so are more familiar and readable than the entries
|
|
in <a href="#Plot">plot</a> files. They are designed to be used in
|
|
further text processing operations or printed as-is. Two spaces are
|
|
placed between each column.<br>
|
|
<br>
|
|
<span style="font-weight: bold;">Selecting data to list<br>
|
|
<br>
|
|
</span>
|
|
<div style="margin-left: 40px;"> Select the <span
|
|
style="font-weight: bold;">Select fields</span> toggle button to
|
|
make each field in the other windows that are eligible for listing
|
|
appear as a pushbutton. Select each such button as desired to define
|
|
each column of the listing. As you make the selections, they are
|
|
listed in the table here. Use the <span style="font-weight: bold;">Undo</span>
|
|
bottom to make changes. Once all the column choices have been made
|
|
return all the windows to their normal operational appearance by
|
|
deselecting the same toggle button. </div>
|
|
<span style="font-weight: bold;"><span style="font-weight: bold;"><br>
|
|
Saving and restoring a plot configuration<br>
|
|
<br>
|
|
</span></span>
|
|
<div style="margin-left: 40px;"> To save this configuration so it can
|
|
be
|
|
loaded later, specify a file name and click <span
|
|
style="font-weight: bold;">Save config file</span>. It will be saved
|
|
in the <a href="file://help/xephem.html#SharedPrivateDirs">Private</a>
|
|
directory. The name of each list item will be saved in addition to the
|
|
column and latex options and title field. The extension for list
|
|
configuration files must be <span style="font-weight: bold;">.lsc</span>
|
|
and will be added automatically if left off.
|
|
A configuration file may be loaded by selecting it from the option
|
|
popup menu to the right of <span style="font-weight: bold;">Load
|
|
config file</span>. The menu will list all files that reside in the
|
|
Shared and Private directories with extension .lsc. Note that reloading
|
|
a configuration only recreates the Listing fields; to be useful, the
|
|
fields to which the reloaded configuration refers must be made active
|
|
independently.<br>
|
|
</div>
|
|
<span style="font-weight: bold;"><span style="font-weight: bold;"></span></span><br>
|
|
<span style="font-weight: bold;"> Specifying the listing file name and
|
|
format<br>
|
|
<br>
|
|
</span>
|
|
<div style="margin-left: 40px;"> Type the <span
|
|
style="font-weight: bold;">name</span> of the file to be used to
|
|
contain the listing in the text field provided. When XEphem first
|
|
needs to write to the file, it will first check for the existence of
|
|
the file and, if it exists, ask whether you wish to append to the
|
|
file or overwrite it.<br>
|
|
<br>
|
|
Choose to print the file in <span style="font-weight: bold;">LaTeX</span>
|
|
table format by pressing the given button before beginning to list to
|
|
the file.<br>
|
|
<br>
|
|
When <span style="font-weight: bold;">column headings</span> are
|
|
turned
|
|
on, they are written to the output file each time the file is
|
|
opened. </div>
|
|
<span style="font-weight: bold;"><br>
|
|
</span>
|
|
<div style="margin-left: 40px;"> All lines within a listing file that
|
|
do
|
|
not begin with an alphanumeric character are considered comments and
|
|
are ignored. When XEphem first writes to a listing file, it will
|
|
place the contents of the <span style="font-weight: bold;">title</span>
|
|
text area, if it is not empty, into the file as a comment for your
|
|
convenience. </div>
|
|
<span style="font-weight: bold;"><br>
|
|
Generating the listing entries<br>
|
|
<br>
|
|
</span>
|
|
<div style="margin-left: 40px;"> Once the fields have been specified
|
|
and
|
|
the listing file named and titled, if desired, select the <span
|
|
style="font-weight: bold;">Create list file</span> toggle button. Now
|
|
each time XEphem goes through one iteration the values you have
|
|
selected
|
|
will be written to the file. Note that when listing is activated,
|
|
XEphem
|
|
does not update the screen until the N Steps count in the Main window <a
|
|
href="#main_looping">looping</a> section goes to 1. This greatly
|
|
speeds
|
|
the creation of plot files by avoiding screen updates. If you wish
|
|
to watch each iteration, set N Steps to 1 and click the Update
|
|
button manually for each iteration.<br>
|
|
<br>
|
|
Once all the desired data have been entered into the listing file,
|
|
toggle the list button back off to flush all data and close the
|
|
file. The windows that contain each of the fields used in the
|
|
listing need not be visible while the list is being generated.
|
|
However, each field must be active, for example its row and column
|
|
must be selected if they are in the Data table. <a name="Search"></a> </div>
|
|
<h2><a class="mozTocH1" name="mozTocId511473"></a> 6.3 Solve equation</h2>
|
|
<img alt="" src="png/solver.png" align="right" height="462" hspace="10"
|
|
width="225">This
|
|
window controls the automatic equation solving facility. You define an
|
|
arithmetic or boolean function, using most of the fields XEphem
|
|
displays, then XEphem will automatically evaluate the function and
|
|
adjust the time on each iteration to solve for the goal. To set up a
|
|
function to solve, follow these steps: Enter a function, Compile it,
|
|
Select a goal, Set the desired accuracy, Enable solving, Start the
|
|
solving process. Each of these steps is described below.<br>
|
|
<br>
|
|
<span style="font-weight: bold;">Entering the function<br>
|
|
<br>
|
|
</span>
|
|
<div style="margin-left: 40px;"> The function may be any arithmetic
|
|
expression, in C-language syntax. All of C's comparison, logical and
|
|
arithmetic operators are supported as well as several common
|
|
arithmetic functions. The complete list is: </div>
|
|
<br>
|
|
<div style="font-family: monospace; margin-left: 80px;"> + - * /
|
|
&& || > >= == != < <= abs floor sin cos tan asin
|
|
acos atan degrad raddeg pi log log10 exp sqrt pow atan2 </div>
|
|
<div style="margin-left: 40px;"> <br>
|
|
The function is entered into the text line provided. It may utilize
|
|
most of the fields from the other XEphem windows. Press the <span
|
|
style="font-weight: bold;">Enable field buttons</span> button to
|
|
make each available field a button. Where ever a field is desired in
|
|
the function, position the text insertion cursor at the desired
|
|
position and select the field; its name will be inserted into the
|
|
function text. When you are finished defining the function, turn off
|
|
the field button appearance by selecting the Enable button again. </div>
|
|
<span style="font-weight: bold;"><br>
|
|
Compiling the function<br>
|
|
<br>
|
|
</span>
|
|
<div style="margin-left: 40px;"> Once the function has been created as
|
|
desired, it must be compiled by selecting the <span
|
|
style="font-weight: bold;">Compile</span> button (or by pressing the
|
|
Enter key on your keyboard). If there are any errors, a diagnostic
|
|
message will appear just below the function. Once a function has
|
|
been successfully compiled, the message will read No compile errors.
|
|
If the function is modified, a message will remind you that it has
|
|
not been compiled. Each time a function is successfully compiled,
|
|
XEphem updates all fields and evaluates the function. As explained
|
|
below, this can be used as an astronomical calculator even when not
|
|
actually solving anything. </div>
|
|
<span style="font-weight: bold;"><br>
|
|
Selecting a goal<br>
|
|
<br>
|
|
</span>
|
|
<div style="margin-left: 40px;"> You may choose from any of four
|
|
evaluation algorithms, as selected by the trio of radio buttons. <span
|
|
style="font-weight: bold;">Find Maximum </span>and <b>Find Minimum</b>
|
|
will solve for a maxima
|
|
or minima of the function, respectively. <span
|
|
style="font-weight: bold;">Find 0</span>
|
|
will solve for a time when the function evaluates to zero. <span
|
|
style="font-weight: bold;">Binary</span> will keep incrementing time
|
|
by <a href="#main_looping">Step</a> until the state of the function
|
|
changes, then do a binary search to find the exact time when the
|
|
function changes state. Binary search interprets a function that
|
|
evaluates to zero to be in one state and all other values to be the
|
|
opposite state. Generally, binary functions are comprised of logical
|
|
operators at their outermost expression levels. </div>
|
|
<span style="font-weight: bold;"><br>
|
|
Specifying the desired accuracy<br>
|
|
<br>
|
|
</span>
|
|
<div style="margin-left: 40px;"> Searching will automatically stop when
|
|
the time changes by less than the desired accuracy value. Note that
|
|
this method of detecting convergence is not based on the value of
|
|
the search function itself. </div>
|
|
<span style="font-weight: bold;"><br>
|
|
Enabling the solver<br>
|
|
<br>
|
|
</span>
|
|
<div style="margin-left: 40px;"> Once the function is defined and it
|
|
compiles without errors, you may enable searching for a solution by
|
|
selecting the button at the top labeled <span
|
|
style="font-weight: bold;">Solving is Active.</span> Then,
|
|
referring now to the <a href="#main_looping">looping</a> section of
|
|
the
|
|
Main window, each time an Update occurs the solution advances by one
|
|
time step until either N Steps iterations have occurred or until
|
|
Step becomes less than Accuracy. The initial time and step size are set
|
|
from the Main window, and are adjusted automatically as the solution
|
|
proceeds. Note that by setting N Steps to 1 and repeatedly selecting
|
|
Update you can effectively single-step the process. Solving will
|
|
automatically turn off when convergence is detected, the function is
|
|
edited or you may turn it off manually at any time by clicking
|
|
Solver is Active back off.<br>
|
|
<br>
|
|
</div>
|
|
<span style="font-weight: bold;"><span style="font-weight: bold;">Saving
|
|
and restoring a solver configuration<br>
|
|
<br>
|
|
</span></span>
|
|
<div style="margin-left: 40px;"> To save the Function, Goal and
|
|
Accuracy
|
|
so it can be loaded later, specify a file name and click <span
|
|
style="font-weight: bold;">Save to</span>. It will be saved in the <a
|
|
href="#SharedPrivateDirs">Private</a> directory. The extension for
|
|
solver configuration files must be <span style="font-weight: bold;">.svc</span>
|
|
and will be added automatically if left off.
|
|
A configuration file may be loaded by selecting it from the option
|
|
popup menu to the right of <span style="font-weight: bold;">Load file</span>.
|
|
The menu will list all files that reside in the Shared and Private
|
|
directories with extension .svc. Note that reloading a solver
|
|
configuration only recreates the solving conditions; to be useful, the
|
|
fields to which the reloaded Function refers must be made active
|
|
independently.<br>
|
|
<br>
|
|
</div>
|
|
<span style="font-weight: bold;">Additional notes on using the
|
|
equation solver:</span><br>
|
|
<br>
|
|
When selecting fields for <a href="#Plot">plotting</a> or <a
|
|
href="#Listing">listing</a> a button appears labeled <span
|
|
style="font-weight: bold;">Use for plotting</span>. You may select
|
|
this button to use the evaluated function as an item in the plot or
|
|
listing feature. Note that the function may be used in plotting or
|
|
listing whether or not actual solving is turned on.<br>
|
|
<p>The windows which contain the fields used in the function being
|
|
solved need not be visible while solving is in progress. However, the
|
|
field must be active, for example their row and column must be
|
|
selected if they are in the Data table.</p>
|
|
<p>The <span style="font-weight: bold;">Close</span> button removes
|
|
the Solving window from the screen; it does not effect actual solver
|
|
operation in any way.</p>
|
|
<p>A successfully compiled function is evaluated each time XEphem
|
|
updates. Whenever the function is compiled it is also evaluated using
|
|
freshly updated values. In this way, the Solve window can actually be
|
|
used as an arbitrary astronomical calculator at any time, whether or
|
|
not solving is actually active.</p>
|
|
<p>Solving periodic functions can lead to solutions far from the
|
|
intended range. You will get best results if you can start the search
|
|
near the expected answer and with a modest step size that will reach
|
|
the the
|
|
nominal solution within a few steps. You can use the <a href="#Plot">plotting</a>
|
|
feature to
|
|
study
|
|
a function and get an idea of the solution, then use the solver
|
|
feature to zero in.<br>
|
|
</p>
|
|
<p>Each plot file may be added to a <a href="#Movie">movie loop</a> or
|
|
overlayed with text or graphical <a href="#Annotation">annotation</a>
|
|
using the menu items in the <b>Control</b> menu of each plot.<br>
|
|
</p>
|
|
<a name="CloseObjects"></a>
|
|
<h2><a class="mozTocH1" name="mozTocId544617"></a> 6.4 Find close pairs</h2>
|
|
<img style="width: 477px; height: 239px;" alt="" title=""
|
|
src="png/close-pairs.png" align="right" hspace="20">This
|
|
window allows you to scan the list of objects currently in memory
|
|
brighter than a given magnitude for all pairs which are separated by
|
|
less than a given angular distance. Separations will be topocentric or
|
|
geocentric depending on the Equatorial <a href="#MainMenu_preferences">Preference</a>
|
|
in the Main menubar. The scan does not include <a href="#FieldStars">field
|
|
stars</a>.<br>
|
|
<br>
|
|
These are the essential steps:<br>
|
|
<ol>
|
|
<li>Set the desired maximum separation, in degrees, and faintest
|
|
magnitude. <br>
|
|
</li>
|
|
<li>Set other options via the Options menu, described below.</li>
|
|
<li>Start the scan via the Run button in the Control menu.</li>
|
|
<li>When the scan completes, all pairs meeting the criteria will
|
|
appear in the scrolled list.<br>
|
|
</li>
|
|
</ol>
|
|
The columns in the list are:<br>
|
|
<ul>
|
|
<li>Object 1 Magnitude</li>
|
|
<li>Object 1 Name</li>
|
|
<li>Object 2 Magnitude</li>
|
|
<li>Object 2 Name</li>
|
|
<li>Separation, in Degrees:Minutes:Seconds<br>
|
|
</li>
|
|
</ul>
|
|
The entries are sorted in increasing order of separation. The total
|
|
number of pairs found and current conditions are reported above the
|
|
list and the time when the scan was performed is indicated in the time
|
|
stamp label below the list. <br>
|
|
<br>
|
|
<a name="CloseObjects_control"></a>
|
|
<h3><a class="mozTocH1" name="mozTocId537600"></a> 6.4.1 Close Pairs Control
|
|
menu</h3>
|
|
<span style="font-weight: bold;">Run</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This performs one scan. The XEphem
|
|
cursor will change to the Watch shape until the scan is complete at
|
|
which time the results appear in the scrolled list. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Sky Point</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This will place a cross-hair over the
|
|
first object of the selected pair on the <a href="#SkyView">Sky View</a>,
|
|
re-aiming if it is currently not in the field. Either select the
|
|
pair in the list then press this button, or double-click on the
|
|
pair in the list. (These commands do nothing if the Sky View is not
|
|
currently up.) </div>
|
|
<br>
|
|
<span style="font-weight: bold;">List to file...</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This selection allows writing the
|
|
current list to a file. A window is presented which allows you to enter
|
|
a file name. The file is written when you click Ok.<br>
|
|
<br>
|
|
The format of the file begins with a header line that captures the
|
|
conditions in effect when the set of close objects was built.
|
|
Following the header, there is one line per pair with exactly the
|
|
same information as appears in the window list. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Close</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This closes the Close Pairs window.
|
|
Note that the <span style="font-weight: bold;">Auto run</span> option
|
|
is
|
|
disabled when the window is closed. </div>
|
|
<a name="CloseObjects_options"></a>
|
|
<h3><a class="mozTocH1" name="mozTocId379485"></a> 6.4.2 Close Pairs Options
|
|
menu</h3>
|
|
<span style="font-weight: bold;">Auto run</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> When this option is active, a scan for
|
|
close objects is performed automatically each time an Update is
|
|
commanded from the Main window. The prior list is discarded each
|
|
time. The scans are not performed if the Close Pairs window is closed. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Auto list</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> When this option is active, the
|
|
results
|
|
of each scan are automatically appended to the file last specified
|
|
in the <span style="font-weight: bold;">List to file</span> window.
|
|
This
|
|
works whether the scan was performed explicitly via the <span
|
|
style="font-family: monospace;">Control » Run</span> command
|
|
here
|
|
or implicitly via an Update from the Main window and the <span
|
|
style="font-weight: bold;">Auto run</span> option is active. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Omit fixed pairs</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> When this option is active, pairs of
|
|
Fixed objects are not listed.<br>
|
|
<br>
|
|
</div>
|
|
<span style="font-weight: bold;">Omit planet's own moons<br>
|
|
<br>
|
|
</span>
|
|
<div style="margin-left: 40px;"> When this option is active, pairs for
|
|
which both objects are part of the same planetary system are not listed.</div>
|
|
<br>
|
|
<a name="CloseObjects_misc"></a>
|
|
<h3><a class="mozTocH3" name="mozTocId201821"></a> 6.4.3 Close Pairs Algorithm</h3>
|
|
<div style="margin-left: 40px;"> The sky dome is broken into bands of
|
|
constant Dec with height equal to the given separation. The database
|
|
is scanned once and each object brighter than the given limit is
|
|
dealt into its band and the one adjacent in the direction of the
|
|
North pole. Each band is then sorted by RA. Each band is then
|
|
scanned for close pairs, with rapid cutoff detection due to the
|
|
sort. The final list is then sorted by separation, and displayed.<br>
|
|
<br>
|
|
Total time is strongly influenced by the number of pairs in the result.
|
|
So when using wide separations it helps to use relatively bright
|
|
limiting magnitudes.<br>
|
|
</div>
|
|
<p><a name="NightAtAGlance"></a></p>
|
|
<h2><a class="mozTocH1" name="mozTocId879084"></a> 6.5 Night at a Glance</h2>
|
|
<img style="width: 450px; height: 400px;" alt="" title=""
|
|
src="png/naag.png" align="right" hspace="20"> This
|
|
window displays a 24 hour period with local midnight in the center.<br>
|
|
<br>
|
|
Across the bottom is a scale marking local dates and time and UTC time,
|
|
at each even hour. The current XEphem time is marked with a thin
|
|
vertical line.<br>
|
|
<br>
|
|
The background gray shading shows when the Sun is up, down and periods
|
|
of twilight. The twilight period matches the Sun Dip setting in the
|
|
Main window <a href="#Main_night_section">Night</a> section.<br>
|
|
<br>
|
|
Overlayed on the gray background is one horizontal line for each <a
|
|
href="#Favorites">Favorite</a>. The lines show when the object is
|
|
above the horizon, the altitude of which is defined in the <span
|
|
style="font-family: monospace;">View » Data Table »
|
|
Control » Setup</span> horizon parameter. The lines on the
|
|
diagram
|
|
pack closer together as the number of objects to display increases; if
|
|
things get too crowded try turning off some of the Favorites.<br>
|
|
<br>
|
|
<span style="font-weight: bold;">NAAG Control menu</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> <span style="font-weight: bold;">One
|
|
color</span> toggles whether objects are drawn all in one color or
|
|
according to their Sky View colors.<br>
|
|
<br>
|
|
<a href="#Print">Print...</a><br>
|
|
<a href="#Favorites">Favorites...</a><br>
|
|
<a href="#Annotation">User annotation...</a><br>
|
|
<a href="#Movie">Add to movie...</a><br>
|
|
<br>
|
|
These buttons provide convenient access to these facilities. </div>
|
|
<span style="font-weight: bold;"><br>
|
|
NAAG mouse<br>
|
|
</span>
|
|
<div style="margin-left: 40px;"> <br>
|
|
Right-clicking near an object's line will pop up a menu
|
|
containing its rise, transit and set data. This information is
|
|
with respect to the day in which the click occurred.<br>
|
|
<br>
|
|
If the mouse is clicked far from any object, then just the time at that
|
|
horizontal position is presented.<br>
|
|
<br>
|
|
The menu always includes a button showing the exact moment
|
|
corresponding to the mouse click position. Clicking the button sets the
|
|
main XEphem time to this moment.<br>
|
|
<br>
|
|
</div>
|
|
An interesting exercise is to set up a time loop with a Step size of
|
|
a few days and watch how the rise and set times of objects and the
|
|
amount and timing of night time are effected throughout the year.<br
|
|
clear="all">
|
|
<br>
|
|
<br>
|
|
<a name="Coord_conv"></a>
|
|
<h2><a class="mozTocH1" name="mozTocId646511"></a> 6.6 Coordinate converter</h2>
|
|
<img alt="" title="" src="png/coordconv.png" align="right" height="187"
|
|
hspace="20" width="403"> This window performs simple conversions
|
|
among several common astronomical coordinate systems. Simply edit (or
|
|
paste) any coordinate and the others will update immediately. All
|
|
fields are in units of Degrees except RA is in Hours. Fields may be
|
|
entered in either sexagesimal or decimal format. For example, either
|
|
10:30:00 or 10.5.<br>
|
|
<br>
|
|
Altitude and Azimuth are with respect to the time and location set in
|
|
the Main window. These will change to correspond to the RA and Dec
|
|
values if an Update is performed.<br>
|
|
<br>
|
|
The top row are astrometric RA and Dec precessed to the given equinox
|
|
year, or enter EOD for apparent coordinates at the current epoch.
|
|
Unlike the other fields, edits to the equinox field only take effect
|
|
on Enter.<br>
|
|
<br>
|
|
The next row are RA and Dec using whatever is set in the Main Window.<br>
|
|
<br>
|
|
The controls across the bottom perform as follows<br>
|
|
<br>
|
|
<blockquote> <b>Close</b><br>
|
|
<blockquote> Closes this window </blockquote>
|
|
<b>Sky Point</b><br>
|
|
<blockquote> Centers the Sky View at the current coordinates. </blockquote>
|
|
<b>Eyepiece</b><br>
|
|
<blockquote> Places an eyepiece in the Sky View at the coordinates
|
|
shown. The Sky View is not recentered. In order to be drawn the Sky
|
|
View
|
|
Eyepieces Option must be turned on. </blockquote>
|
|
<b>Get Sky</b><br>
|
|
<blockquote> Loads each field from the current center position of the
|
|
Sky View. </blockquote>
|
|
<b>Canonize</b><br>
|
|
<blockquote> Reformats each field in a consistent manner for easier
|
|
viewing. </blockquote>
|
|
</blockquote>
|
|
<a name="obslog"></a>
|
|
<h2><a class="mozTocH2" name="mozTocId535879"></a> 6.7 <a name="ObsLog"></a>Observers
|
|
logbook</h2>
|
|
<img alt="" src="png/obslog.png" align="right" height="739" hspace="10"
|
|
width="293">This
|
|
tool lets you store observing circumstances and notes. It is typically
|
|
used when making observations at the
|
|
telescope.<br>
|
|
<br>
|
|
When this window is open, the popup you get when right-clicking on an
|
|
object in the Sky View will contain a selection <span
|
|
style="font-weight: bold;">Add to logbook</span>. Clicking on this
|
|
choice will automatically fill in the top section of fields in the
|
|
logbook pertaining to
|
|
observing
|
|
circumstances and object information. To these fields you may add your
|
|
own <span style="font-weight: bold;">Notes</span> in the scrolled text
|
|
area at
|
|
the bottom, and equipment or <span style="font-weight: bold;">User
|
|
defined fields</span> if desired.<br>
|
|
<br>
|
|
There are two interesting controls available across the bottom as
|
|
follows:<br>
|
|
<b><br>
|
|
</b>
|
|
<div style="margin-left: 40px;"><b> List</b></div>
|
|
<br>
|
|
<div style="margin-left: 80px;"> This brings up a scrolled list showing
|
|
all entries in the logbook whose fields match those selected in the <b>S</b>
|
|
column. The field may contain <a href="#glob">glob</a> patterns
|
|
for a textual match or be
|
|
preceded with < or > for a numerical range match. Only those
|
|
fields selected with the<b> L</b> column will be
|
|
shown, and they may be sorted by the field selected in the<b> K</b>
|
|
column.<br>
|
|
<br>
|
|
You may <b>Save</b> the resulting scrolled list to a text file using
|
|
the
|
|
file name field provided. Right-clicking on an entry in the scrolled
|
|
list will mark the location of that log entry in the Sky View based on
|
|
its RA2000 and Dec2000 field values.<br>
|
|
<br>
|
|
<img alt="" src="png/obslog-list.png" align="top" height="178"
|
|
width="453"><br>
|
|
</div>
|
|
<div style="margin-left: 40px;"> <span style="font-weight: bold;"><br>
|
|
<br>
|
|
<br>
|
|
</span></div>
|
|
<div style="margin-left: 40px;"> <b>Add</b></div>
|
|
<br>
|
|
<div style="margin-left: 80px;"> This will add the current record to
|
|
the
|
|
logbook file. In keeping with the convention that log books are written
|
|
in ink, there is no mechanism provided for editing or removing existing
|
|
entries. Of course, one may always edit the log file independently.<br>
|
|
</div>
|
|
<br>
|
|
<span style="font-weight: bold;">File format</span><br>
|
|
<br>
|
|
The Observers logbook is a text file in XML format. The format should
|
|
be pretty self-explanatory. The file name is <span
|
|
style="font-weight: bold;">xelogbook.xml</span> in the Private
|
|
directory. The entire logbook is
|
|
contained in one XML element tagged <span style="font-weight: bold;">xelogbook
|
|
</span>with a version attribute 1.1.
|
|
Each log entry is in an element tagged <span style="font-weight: bold;">logentry</span>.
|
|
Within each logentry is
|
|
one element named the same as the label in the window, sans spaces if
|
|
any. The date fields are stored in the user's preferred format.<br>
|
|
<br>
|
|
<br>
|
|
<br clear="all">
|
|
<h2><a class="mozTocH2" name="mozTocId617264"></a> 6.8 <a name="Movie"></a>Movie
|
|
loop</h2>
|
|
<img alt="" src="png/movie.png" align="right" height="324" hspace="10"
|
|
width="411">The Movie tool allows you to capture any
|
|
number of View, <a href="#NightAtAGlance">Night at a Glance</a> or <a
|
|
href="#Plot">Plot</a> windows and collect them into a movie. The
|
|
frames of the movie can be viewed one at a time or you can set the rate
|
|
to change from one frame to next automatically. There are many uses for
|
|
this type of function. For example, you could make small changes in
|
|
time and make a series showing the movement of an asteroid through the
|
|
solar system. Or use it to quickly blink between two FITS images, one
|
|
with and one without a potentially new supernova. You might find the <a
|
|
href="#imreg">Image Registration</a> feature useful to make these
|
|
images.<br>
|
|
<br>
|
|
The <b>Control</b> menu has entries to <b>Delete current</b> frame or
|
|
<b>Delete all</b> frames of the movie. You may also <b>Save</b> the
|
|
frames to individual PNG files. You must specify a prefix then each
|
|
file name will be of the format prefixnnn.png where <i>nnn</i> will be
|
|
a sequence number starting with 000. The files will be located in the <a
|
|
href="#SharedPrivateDirs">Private</a> directory. XEphem does not save
|
|
the frames directly as an actual movie because there are many such
|
|
formats and other tools available to collect the files into a movie in
|
|
your preferred format. For example, you could convert the PNG files
|
|
into GIF files using <em>pngtopnm</em> and <em>ppmtogif</em> tools
|
|
from the <a target="netpbm" href="http://netpbm.sourceforge.net">netpbm</a>
|
|
toolkit then make an
|
|
animated gif using <a target="whirlgif"
|
|
href="http://www.danbbs.dk/%7Edino/whirlgif">whirlgif</a>
|
|
or <a target="gifsicle" href="http://www.lcdf.org/%7Eeddietwo/gifsicle">gifsicle</a>.
|
|
Another possibility is to use <em>convert</em> which is part of the
|
|
<a target="imagemagick" href="http://www.imagemagick.org">ImageMagick</a>
|
|
collection. Check your system before looking too far, these tools are
|
|
often
|
|
already installed on many UN*X systems.<br>
|
|
<br>
|
|
Sliding the <b>Frame selection</b> scale will display the indicated
|
|
frame. <b>Step +1</b> and <b>-1</b> will advance or back up by one
|
|
frame. Frames may also be changed automatically by sliding the <b>Frames
|
|
per second</b> scale to the desired rate. Changing the displayed frame
|
|
manually by any means will automatically reset the frame rate back to
|
|
zero. When moving through the frames automatically and encountering the
|
|
last frame in the series, the sequence can either reverse and show each
|
|
frame back towards the first or jump back to the first and move
|
|
forwards again, depending on the <b>Bounce</b> toggle button.<br>
|
|
<br>
|
|
Each window whose contents may be added to a Movie will have an entry
|
|
somewhere in its menu bar named "Add to movie". All such windows also
|
|
support a short cut of typing Control-m to add the window to the Movie,
|
|
so long as the cursor focus is located within the desired window.<br
|
|
clear="all">
|
|
<h1><a class="mozTocH1" name="mozTocId36368"></a> 7.0 <b>Data menu</b></h1>
|
|
The Data menu offers several means to load, search and update the
|
|
files XEphem uses for storing objects.<br clear="all">
|
|
<br>
|
|
<a name="Database"></a>
|
|
<h2><a class="mozTocH1" name="mozTocId132979"></a> 7.1 Files</h2>
|
|
<img style="width: 285px; height: 400px;" alt="" title=""
|
|
src="png/db.png" align="right" hspace="20"> This
|
|
window allows you to load and delete database files to and from memory.
|
|
These objects form what is referred to as the XEphem database. These do
|
|
<i>not</i>
|
|
include the <a href="#FieldStars">field stars</a>.<br>
|
|
<br>
|
|
Click the <b>Files</b> menu to scan the <a href="#SharedPrivateDirs">Private
|
|
and Shared</a> directories and pop up a list of all .edb and .tle files
|
|
found therein. Click on a file to load it into XEphem memory.<br>
|
|
<br>
|
|
The top section of the window displays a count of each major type of
|
|
object and the total number in the database. The counts include <a
|
|
href="#Favorites">Favorites</a> that are not also in the database.<br>
|
|
<br>
|
|
The bottom section lists the catalogs which are currently loaded and
|
|
the number of new objects they contributed to memory. Buttons to the
|
|
left of each catalog allow the catalog to be <span
|
|
style="font-weight: bold;">Delete</span>d from memory and to display
|
|
the <span style="font-weight: bold;">Header</span> of the catalog.<br>
|
|
<br>
|
|
The current list of loaded catalogs may be saved so it becomes the
|
|
ones automatically loaded when XEphem starts. To do so, go to <span
|
|
style="font-family: monospace;">Preferences » Save</span> and <a
|
|
href="#Save">Save</a> the XEphem.DBInitialFiles resource under the
|
|
Data Base category.<br>
|
|
<br>
|
|
<h3><a class="mozTocH1" name="mozTocId356973"></a> 7.1.1 <a
|
|
name="Database_control"></a>Files Control menu</h3>
|
|
<b>Index...<br>
|
|
</b>
|
|
<blockquote>This is a handy shortcut to open the <a href="#Object">object
|
|
index</a>.<br>
|
|
</blockquote>
|
|
<b>Delete all<br>
|
|
</b>
|
|
<blockquote> This deletes all loaded data. The files on disk are not
|
|
effected. </blockquote>
|
|
<b>Reload all</b><br>
|
|
<blockquote> This reloads all catalogs currently loaded. This is handy
|
|
when catalogs have been updated on disk, perhaps by some by some
|
|
automatic means. </blockquote>
|
|
<b>Open DB Fifo<br>
|
|
</b>
|
|
<blockquote> Listen for database objects arriving via a fifo from
|
|
another process. XEphem attempts to reopen the fifo each time the
|
|
button
|
|
is pressed. The file name of this fifo is <span
|
|
style="font-weight: bold;">"</span>fifos/xephem_db_fifo" in either the
|
|
Private or Shared directory. All relevant displays are automatically updated
|
|
when data arrives via this fifo. The format of the fifo data is
|
|
exactly the same as for any XEphem database file. Due to the way the
|
|
fifo data is read and processed, it is important that each line be
|
|
terminated with a newline; incomplete last lines can result in loss
|
|
of information. </blockquote>
|
|
<b>Make Favorite when read 1<br>
|
|
</b>
|
|
<blockquote> If this toggle is on then when a new database file is
|
|
loaded and it defines exactly one object, it will also be assigned to
|
|
the list of <a href="#Favorites">Favorites</a>. This feature also
|
|
applies for files loaded when XEphem first starts.<br>
|
|
</blockquote>
|
|
<b>Check alternate names</b><br>
|
|
<blockquote>This toggle turns on or off support for XEphem 3.6's new
|
|
support for alternate names. It is motivated entirely by performance.
|
|
Recording alternate names and checking for duplicates is quite
|
|
expensive and
|
|
if not needed can speed up loading and deleting catalogs significantly.
|
|
If this toggle is On then when a new database
|
|
catalog is loaded each entry's alternate names, if any, will be checked
|
|
for
|
|
already being loaded and not loaded if found, and new alternates will
|
|
be
|
|
stored for display and subsequent checking. If this toggle is Off, only
|
|
the
|
|
first name of each entry is stored and no duplicate names are checked.
|
|
Note that even when this option is Off, deleting a catalog still
|
|
requires
|
|
XEphem to remove all alternate names that might have been recorded when
|
|
the
|
|
catalog was loaded, so the full performance advantage is only achieved
|
|
if this
|
|
option was off when each catalog is loaded.<br>
|
|
</blockquote>
|
|
<blockquote> </blockquote>
|
|
<b>Close</b><br>
|
|
<blockquote> Closes the Data Base window. <a name="Database_files"></a>
|
|
</blockquote>
|
|
<h3><a class="mozTocH1" name="mozTocId468501"></a> 7.1.2 File format</h3>
|
|
This section describes the format of an XEphem database file. The
|
|
file name extension is .edb. See the next section for files containing
|
|
two-line Earth satellite elements.<br>
|
|
<h4><a class="mozTocH4" name="mozTocId800642"></a> 7.1.2.1 <b>General format
|
|
rules<br>
|
|
</b></h4>
|
|
<ul>
|
|
<li>Each object occupies one line in the file.</li>
|
|
<li>The order of objects in a file does not matter.</li>
|
|
<li>Lines beginning with anything other than a-z, A-Z or 0-9 are
|
|
ignored and may be used for comments.</li>
|
|
<li>Lines are separated into Fields using commas (,).</li>
|
|
<li>Fields may be further subdivided into Subfields with vertical
|
|
bars (|).</li>
|
|
<li>All date fields may be in either of two forms:</li>
|
|
</ul>
|
|
<blockquote>
|
|
<ol>
|
|
<li>month/day/year, where day may contain a fractional portion.
|
|
examples: 1/1/1993 and 1/1.234/1993 . Note the format of dates in
|
|
database files is always M/D/Y, regardless of the current XEphem
|
|
Date format <a href="#MainMenu_preferences">Preference</a> setting; or<br>
|
|
<br>
|
|
</li>
|
|
<li>the year as real number as indicated by the presence of a
|
|
decimal point, such as 1993.123.<br>
|
|
</li>
|
|
</ol>
|
|
</blockquote>
|
|
<h4><a class="mozTocH4" name="mozTocId215848"></a> 7.1.2.2 <span
|
|
style="font-weight: bold;">Format Details</span></h4>
|
|
<div style="margin-left: 40px;"> The first two fields are required and
|
|
are always Name and Type. Remaining fields depend on Type. </div>
|
|
<br>
|
|
<table style="text-align: left; width: 95%; margin-left: 80px;"
|
|
summary=".edb fields 1 and 2" cellpadding="2" cellspacing="2">
|
|
<tbody>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 100px;"><span
|
|
style="font-weight: bold;">Field 1</span><br>
|
|
</td>
|
|
<td style="vertical-align: top;">One or more object names, each
|
|
separated by the Subfield separator, |. Any number of characters may be
|
|
present in the file but XEphem only uses the first 20 characters of
|
|
each name and only the first 20 names.<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 100px;"><span
|
|
style="font-weight: bold;">Field 2</span></td>
|
|
<td style="vertical-align: top;"> Type designation. Consists of a
|
|
single letter designation from the following set (case <span
|
|
style="font-style: italic;">is</span> significant):<br>
|
|
<table style="text-align: left; width: 95%;" summary="field 2"
|
|
border="0" cellpadding="2" cellspacing="2">
|
|
<tbody>
|
|
<tr>
|
|
<td style="vertical-align: top; font-weight: bold;"> f<br>
|
|
</td>
|
|
<td style="vertical-align: top;">fixed (or at most exhibits
|
|
constant curvilinear proper motion)</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-weight: bold;"> e<br>
|
|
</td>
|
|
<td style="vertical-align: top;">heliocentric elliptical
|
|
orbit</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-weight: bold;"> h<br>
|
|
</td>
|
|
<td style="vertical-align: top;">heliocentric hyperbolic
|
|
orbit</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-weight: bold;"> p<br>
|
|
</td>
|
|
<td style="vertical-align: top;">heliocentric parabolic
|
|
orbit</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-weight: bold;"> E<br>
|
|
</td>
|
|
<td style="vertical-align: top;">geocentric elliptical
|
|
orbit, <span style="font-style: italic;">i.e.</span>, Earth satellite</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-weight: bold;"> P<br>
|
|
</td>
|
|
<td style="vertical-align: top;">built-in planet or natural
|
|
satellite name</td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
</td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
<br>
|
|
<div style="margin-left: 40px;"> <span style="font-weight: normal;">If</span>
|
|
<span style="font-weight: bold;">Field 2</span> <span
|
|
style="font-weight: normal;"> is</span><span style="font-weight: bold;">
|
|
f</span> <span style="font-weight: normal;"> the object is fixed and
|
|
the
|
|
following fields and subfields are defined:<br>
|
|
<br>
|
|
</span> </div>
|
|
<div style="margin-left: 80px;">
|
|
<table style="text-align: left; width: 95%;" summary="field 2"
|
|
border="0" cellpadding="2" cellspacing="2">
|
|
<tbody>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 100px;"><br>
|
|
</td>
|
|
<td style="vertical-align: top; width: 100px;"> <b>SubField 2A</b></td>
|
|
<td style="vertical-align: top;"> An optional SubField 2A can be
|
|
added to further define an object class code, consisting of
|
|
one character from the following list:<br>
|
|
<table style="text-align: left; width: 100%;"
|
|
summary="subfield 2a" border="0" cellpadding="2" cellspacing="2">
|
|
<tbody>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 20px;"> A<br>
|
|
</td>
|
|
<td style="vertical-align: top;">Cluster of galaxies</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 20px;"> B<br>
|
|
</td>
|
|
<td style="vertical-align: top;">Star, binary. Deprecated
|
|
as of version 3.6, gets turned into D internally. Use Field 2
|
|
type <b>B </b>if more than one position angle and separation or
|
|
orbital elements are
|
|
known.<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 20px;"> C<br>
|
|
</td>
|
|
<td style="vertical-align: top;">Cluster, globular</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 20px;"> D<br>
|
|
</td>
|
|
<td style="vertical-align: top;">Star, visual double</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 20px;"> F<br>
|
|
</td>
|
|
<td style="vertical-align: top;">Nebula, diffuse</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 20px;"> G<br>
|
|
</td>
|
|
<td style="vertical-align: top;">Galaxy, spiral</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 20px;"> H<br>
|
|
</td>
|
|
<td style="vertical-align: top;">Galaxy, spherical</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 20px;"> J<br>
|
|
</td>
|
|
<td style="vertical-align: top;">Radio</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 20px;"> K<br>
|
|
</td>
|
|
<td style="vertical-align: top;">Nebula, dark</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 20px;"> L<br>
|
|
</td>
|
|
<td style="vertical-align: top;">Pulsar</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 20px;"> M<br>
|
|
</td>
|
|
<td style="vertical-align: top;">Star, multiple</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 20px;"> N<br>
|
|
</td>
|
|
<td style="vertical-align: top;">Nebula, bright</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 20px;"> O<br>
|
|
</td>
|
|
<td style="vertical-align: top;">Cluster, open</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 20px;"> P<br>
|
|
</td>
|
|
<td style="vertical-align: top;">Nebula, planetary</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 20px;"> Q<br>
|
|
</td>
|
|
<td style="vertical-align: top;">Quasar</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 20px;"> R<br>
|
|
</td>
|
|
<td style="vertical-align: top;">Supernova remnant</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 20px;"> S<br>
|
|
</td>
|
|
<td style="vertical-align: top;">Star</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 20px;"> T<br>
|
|
</td>
|
|
<td style="vertical-align: top;">Stellar object</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 20px;"> U<br>
|
|
</td>
|
|
<td style="vertical-align: top;">Cluster, with nebulosity</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top;">Y<br>
|
|
</td>
|
|
<td style="vertical-align: top;">Supernova<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 20px;"> V<br>
|
|
</td>
|
|
<td style="vertical-align: top;">Star, variable</td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 100px;"><br>
|
|
</td>
|
|
<td style="vertical-align: top; width: 100px;"> <b>SubField 2B</b></td>
|
|
<td style="vertical-align: top;">If SubField 2A is one of T, B,
|
|
D, S or V, optional SubField 2B may consist of up to two spectral
|
|
designation characters, typically one letter followed by one numerical
|
|
subclass designator. Two examples are O and G3.</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top;"><br>
|
|
</td>
|
|
<td style="vertical-align: top;"><br>
|
|
</td>
|
|
<td style="vertical-align: top;">If SubField 2A is any other
|
|
class code, optional SubField 2B may consist of up to two additional
|
|
characters to further describe the type.<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 100px;"><b>Field 3</b></td>
|
|
<td colspan="2" rowspan="1" style="vertical-align: top;"> Astrometric RA
|
|
position coordinate in equinox given by Field 6 always at epoch 2000, given as H:M:S.</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 100px;"><br>
|
|
</td>
|
|
<td style="vertical-align: top; width: 100px;"> <span
|
|
style="font-weight: bold;">SubField 3A</span></td>
|
|
<td style="vertical-align: top;">This optional subfield may
|
|
specify a proper motion in RA. It is in milliarcseconds per
|
|
year on the sky, <span style="font-style: italic;">i.e.</span>, <span
|
|
style="font-family: monospace;">ΔRA*cos(dec)</span>.</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 100px;"><b>Field 4</b></td>
|
|
<td colspan="2" rowspan="1" style="vertical-align: top;">Astrometric Declination
|
|
position coordinate in equinox given by Field 6 always at epoch 2000, given as D:M:S.</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 100px;"><br>
|
|
</td>
|
|
<td style="vertical-align: top; width: 100px;"> <b>SubField 4A</b></td>
|
|
<td style="vertical-align: top;">This optional subfield may
|
|
specify a proper motion in Dec. It is in milliarcseconds per
|
|
year on the sky</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-weight: bold; width: 100px;">Field
|
|
5<br>
|
|
</td>
|
|
<td colspan="2" rowspan="1" style="vertical-align: top;">Magnitude
|
|
of the object.</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-weight: bold; width: 100px;">Field
|
|
6<br>
|
|
</td>
|
|
<td colspan="2" rowspan="1" style="vertical-align: top;"> This
|
|
optional field is the reference epoch. It is assumed to be
|
|
2000 if absent</td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
</div>
|
|
<div style="margin-left: 40px;">
|
|
<div style="margin-left: 40px;"> <b><br>
|
|
</b><br>
|
|
<table style="text-align: left; width: 95%;" summary="field" border="0"
|
|
cellpadding="2" cellspacing="2">
|
|
<tbody>
|
|
<tr>
|
|
<td colspan="3" rowspan="1" style="vertical-align: top;"><span
|
|
style="font-weight: bold;">Field 7</span> depends on SubField 2A</td>
|
|
</tr>
|
|
<tr>
|
|
<td colspan="3" rowspan="1"
|
|
style="vertical-align: top; width: 100px;">If SubField 2A is <span
|
|
style="font-weight: bold;">G</span>
|
|
or <span style="font-weight: bold;">H</span></td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top;"><span style="font-weight: bold;">Field
|
|
7</span><br>
|
|
</td>
|
|
<td colspan="2" rowspan="1" style="vertical-align: top;">Galaxy
|
|
major axis, in arcseconds</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 100px;"><br>
|
|
</td>
|
|
<td style="vertical-align: top; width: 100px;"> <b>SubField 7A</b></td>
|
|
<td style="vertical-align: top;">Galaxy minor axis, in arcseconds</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 100px;"><br>
|
|
</td>
|
|
<td style="vertical-align: top; width: 100px;"> <b>SubField 7B</b></td>
|
|
<td style="vertical-align: top;">Major axis position angle, in
|
|
degrees East of North</td>
|
|
</tr>
|
|
<tr>
|
|
<td colspan="3" rowspan="1"
|
|
style="vertical-align: top; width: 100px;">If Subfield 2A is <span
|
|
style="font-weight: bold;">B</span>
|
|
or <span style="font-weight: bold;">D</span></td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top;"><span style="font-weight: bold;">Field
|
|
7</span></td>
|
|
<td colspan="2" rowspan="1" style="vertical-align: top;">star
|
|
pair separation, in arcseconds<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 100px;"><br>
|
|
</td>
|
|
<td style="vertical-align: top; width: 100px;"> <b>SubField 7A</b></td>
|
|
<td style="vertical-align: top;">reserved, set to 0</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 100px;"><br>
|
|
</td>
|
|
<td style="vertical-align: top; width: 100px;"> <b>SubField 7B</b></td>
|
|
<td style="vertical-align: top;">position angle, in degrees East
|
|
of North</td>
|
|
</tr>
|
|
<tr>
|
|
<td colspan="3" rowspan="1"
|
|
style="vertical-align: top; width: 100px;">Otherwise Field 7 is
|
|
optional but if present</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top;"><span style="font-weight: bold;">Field
|
|
7</span></td>
|
|
<td colspan="2" rowspan="1" style="vertical-align: top;">size of
|
|
the object, in arcseconds. It is assumed to be 0 if absent.</td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
</div>
|
|
</div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> <span style="font-weight: normal;">If</span>
|
|
<span style="font-weight: bold;">Field 2</span> <span
|
|
style="font-weight: normal;"> is</span><span style="font-weight: bold;">
|
|
B</span> <span style="font-weight: normal;"> the object is a true
|
|
binary pair and
|
|
the
|
|
following fields and subfields are defined.<br>
|
|
<br>
|
|
</span> </div>
|
|
<div style="margin-left: 80px;">
|
|
<table style="text-align: left; width: 95%;" summary="field 2"
|
|
border="0" cellpadding="2" cellspacing="2">
|
|
<tbody>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 100px;"><br>
|
|
</td>
|
|
<td style="vertical-align: top; width: 100px;"> <b>SubField 2A</b></td>
|
|
<td style="vertical-align: top;"> An optional SubField 2A can be
|
|
added to further define an binary class code, consisting of
|
|
one character from the following list. This scheme is taken from the
|
|
Washington Multiplicity catalog for compliance with the IAU 2003
|
|
recommendation.<br>
|
|
<table style="text-align: left; width: 100%;"
|
|
summary="subfield 2a" border="0" cellpadding="2" cellspacing="2">
|
|
<tbody>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 20px;"> a<br>
|
|
</td>
|
|
<td style="vertical-align: top;">Astrometric binary<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 20px;"> c<br>
|
|
</td>
|
|
<td style="vertical-align: top;">Cataclysmic variable<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 20px;"> e<br>
|
|
</td>
|
|
<td style="vertical-align: top;">Eclipsing binary<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 20px;"> x<br>
|
|
</td>
|
|
<td style="vertical-align: top;">High-mass X-ray binary<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 20px;"> y<br>
|
|
</td>
|
|
<td style="vertical-align: top;">Low-mass X-ray binary<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 20px;"> o<br>
|
|
</td>
|
|
<td style="vertical-align: top;">Occultation binary<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 20px;"> s<br>
|
|
</td>
|
|
<td style="vertical-align: top;">Spectroscopic binary<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 20px;"> t<br>
|
|
</td>
|
|
<td style="vertical-align: top;">Single-line spectroscopic
|
|
binary<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 20px;"> u<br>
|
|
</td>
|
|
<td style="vertical-align: top;">Double-line spectroscopic
|
|
binary<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 20px;"> v<br>
|
|
</td>
|
|
<td style="vertical-align: top;">Spectrum binary<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td valign="top">b<br>
|
|
</td>
|
|
<td valign="top">Visual binary<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td valign="top">d<br>
|
|
</td>
|
|
<td valign="top">Visual binary with common proper motion<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td valign="top">q<br>
|
|
</td>
|
|
<td valign="top">Visual binary - optical<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td valign="top">r<br>
|
|
</td>
|
|
<td valign="top">Visual binary - physical<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 20px;"> p<br>
|
|
</td>
|
|
<td style="vertical-align: top;">Exoplanet<br>
|
|
</td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 100px;"><br>
|
|
</td>
|
|
<td style="vertical-align: top; width: 100px;"> <b>SubField 2B</b></td>
|
|
<td style="vertical-align: top;">Up to two characters to specify
|
|
the spectral class of the primary star, typically one letter followed
|
|
by one numerical subclass designator. Two examples are O and G3.</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top;"><br>
|
|
</td>
|
|
<td style="vertical-align: top;"><b>SubField 2C</b> </td>
|
|
<td style="vertical-align: top;">Up to two characters to specify
|
|
the spectral class of the secondary star,
|
|
typically one letter followed by one numerical subclass designator.
|
|
Two examples are O and G3. </td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 100px;"><b>Field 3</b></td>
|
|
<td colspan="2" rowspan="1" style="vertical-align: top;"> RA
|
|
position coordinate, given as H:M:S.</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 100px;"><br>
|
|
</td>
|
|
<td style="vertical-align: top; width: 100px;"> <span
|
|
style="font-weight: bold;">SubField 3A</span></td>
|
|
<td style="vertical-align: top;">This optional subfield may
|
|
specify a proper motion in RA. It is in milliarcseconds per
|
|
year on the sky, <span style="font-style: italic;">i.e.</span>, <span
|
|
style="font-family: monospace;">ΔRA*cos(dec)</span>.</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 100px;"><b>Field 4</b></td>
|
|
<td colspan="2" rowspan="1" style="vertical-align: top;">Declination
|
|
position coordinate, given as D:M:S.</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 100px;"><br>
|
|
</td>
|
|
<td style="vertical-align: top; width: 100px;"> <b>SubField 4A</b></td>
|
|
<td style="vertical-align: top;">This optional subfield may
|
|
specify a proper motion in Dec. It is in milliarcseconds per
|
|
year on the sky</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-weight: bold; width: 100px;">Field
|
|
5<br>
|
|
</td>
|
|
<td colspan="2" rowspan="1" style="vertical-align: top;">Magnitude
|
|
of each star in the pair.</td>
|
|
</tr>
|
|
<tr>
|
|
<td valign="top"><br>
|
|
</td>
|
|
<td valign="top"><b>SubField 5A</b><br>
|
|
</td>
|
|
<td valign="top">Magnitude of the primary star<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td valign="top"><br>
|
|
</td>
|
|
<td valign="top"><b>SubField 5B</b><br>
|
|
</td>
|
|
<td valign="top">Magnitude of the secondary star<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-weight: bold; width: 100px;">Field
|
|
6<br>
|
|
</td>
|
|
<td colspan="2" rowspan="1" style="vertical-align: top;"> This
|
|
optional field is the reference equinox year. It is assumed to be
|
|
2000 if absent</td>
|
|
</tr>
|
|
<tr>
|
|
<td valign="top"><b>Field 7</b><br>
|
|
</td>
|
|
<td colspan="2" rowspan="1" valign="top">This field may contain
|
|
either 3 or 6 subfields (one or two triples of year/separation/position
|
|
angle)
|
|
or 7 subfields (orbital elements).<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td valign="top"><br>
|
|
</td>
|
|
<td colspan="2" rowspan="1" valign="top">If 3 or 6 subfields,
|
|
they define positions grouped as the following triplets:<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td valign="top"><br>
|
|
</td>
|
|
<td valign="top"><b>SubField 7A/D</b></td>
|
|
<td valign="top">Year of the separation and position angle given
|
|
in the next two fields, decimal year or month/day/year </td>
|
|
</tr>
|
|
<tr>
|
|
<td valign="top"><br>
|
|
</td>
|
|
<td valign="top"><b>SubField 7B/E</b></td>
|
|
<td valign="top">Separation, arc seconds<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td valign="top"><br>
|
|
</td>
|
|
<td valign="top"><b>SubField 7C/F</b></td>
|
|
<td valign="top">Position angle, degrees E of N, referenced to
|
|
equinox in field 6<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td valign="top"><br>
|
|
</td>
|
|
<td colspan="2" rowspan="1" valign="top">If 7 subfields, they
|
|
define a
|
|
true orbit:<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td valign="top"><br>
|
|
</td>
|
|
<td valign="top"><b>SubField 7A</b><br>
|
|
</td>
|
|
<td valign="top">Semi-major axis, arcseconds<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td valign="top"><br>
|
|
</td>
|
|
<td valign="top"><b>SubField 7B</b></td>
|
|
<td valign="top">Inclination from plane of sky, degrees<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td valign="top"><br>
|
|
</td>
|
|
<td valign="top"><b>SubField 7C</b></td>
|
|
<td valign="top">Longitude of node, degrees<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td valign="top"><br>
|
|
</td>
|
|
<td valign="top"><b>SubField 7D</b></td>
|
|
<td valign="top">Eccentricity<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td valign="top"><br>
|
|
</td>
|
|
<td valign="top"><b>SubField 7E</b></td>
|
|
<td valign="top">Epoch of periastron, decimal year or
|
|
month/day/year<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td valign="top"><br>
|
|
</td>
|
|
<td valign="top"><b>SubField 7F</b></td>
|
|
<td valign="top">Argument of periastron, degrees<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td valign="top"><br>
|
|
</td>
|
|
<td valign="top"><b>SubField 7G</b></td>
|
|
<td valign="top">Period. Units are designated by suffix <b>y</b>
|
|
for years, <b>d</b> for days, or <b>h</b> for hours. If no
|
|
designation the default is years.<br>
|
|
</td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
</div>
|
|
<br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> If <span style="font-weight: bold;">Field
|
|
2</span> is <span style="font-weight: bold;">e</span> the object type
|
|
is
|
|
elliptical heliocentric (eccentricity < 1) and the remaining fields
|
|
are defined as follows: </div>
|
|
<br>
|
|
<div style="margin-left: 40px;">
|
|
<div style="margin-left: 40px;">
|
|
<table style="text-align: left; width: 95%;" summary="elliptical fields"
|
|
border="0" cellpadding="2" cellspacing="2">
|
|
<tbody>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 100px; font-weight: bold;">Field
|
|
3<br>
|
|
</td>
|
|
<td colspan="2" rowspan="1" style="vertical-align: top;">i =
|
|
inclination, degrees</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 100px; font-weight: bold;">Field
|
|
4<br>
|
|
</td>
|
|
<td colspan="2" rowspan="1" style="vertical-align: top;">O =
|
|
longitude of ascending node, degrees</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 100px; font-weight: bold;">Field
|
|
5<br>
|
|
</td>
|
|
<td colspan="2" rowspan="1" style="vertical-align: top;">o =
|
|
argument of perihelion, degrees</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 100px; font-weight: bold;">Field
|
|
6<br>
|
|
</td>
|
|
<td colspan="2" rowspan="1" style="vertical-align: top;">a = mean
|
|
distance (aka semi-major axis), AU</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 100px; font-weight: bold;">Field
|
|
7<br>
|
|
</td>
|
|
<td colspan="2" rowspan="1" style="vertical-align: top;">n = mean
|
|
daily motion, degrees per day (computed from a**3/2 if
|
|
omitted)</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 100px; font-weight: bold;">Field
|
|
8<br>
|
|
</td>
|
|
<td colspan="2" rowspan="1" style="vertical-align: top;">e =
|
|
eccentricity, must be < 1<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 100px; font-weight: bold;">Field
|
|
9<br>
|
|
</td>
|
|
<td colspan="2" style="vertical-align: top;">M = mean anomaly,
|
|
i.e., degrees from perihelion</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 100px; font-weight: bold;">Field
|
|
10<br>
|
|
</td>
|
|
<td colspan="2" style="vertical-align: top;">E = epoch date,
|
|
i.e., time of M</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top;"><br>
|
|
</td>
|
|
<td style="vertical-align: top; width: 100px;"><b>SubField 10A</b></td>
|
|
<td style="vertical-align: top;">First date these elements are
|
|
valid, optional<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top;"><br>
|
|
</td>
|
|
<td style="vertical-align: top; width: 100px;"><b>SubField 10B</b></td>
|
|
<td style="vertical-align: top;">Last date these elements are
|
|
valid, optional<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 100px; font-weight: bold;">Field
|
|
11<br>
|
|
</td>
|
|
<td colspan="2" style="vertical-align: top;">D = the equinox
|
|
year, i.e., time of i, O and o</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; width: 100px; font-weight: bold;">Field
|
|
12<br>
|
|
</td>
|
|
<td colspan="2" style="vertical-align: top;">First component of
|
|
magnitude model, either g from (g,k) or
|
|
H from (H,G). Specify which by preceding the number with a "g"
|
|
or an "H". In absence of either specifier the default is (H,G) model.
|
|
See <a href="#mag_models">Magnitude models</a>.</td>
|
|
</tr>
|
|
<tr>
|
|
<td valign="top"><b>Field 13</b><br>
|
|
</td>
|
|
<td colspan="2" rowspan="1" valign="top">Second component of
|
|
magnitude model, either k or G<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td valign="top"><b>Field 14</b><br>
|
|
</td>
|
|
<td colspan="2" rowspan="1" valign="top">s =
|
|
angular size at 1 AU, arc seconds, optional</td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
</div>
|
|
<div style="margin-left: 40px;"> <span style="font-weight: bold;"><br>
|
|
</span> </div>
|
|
</div>
|
|
<div style="margin-left: 80px;"> You may have other parameters
|
|
available
|
|
for elliptical orbits that can be converted into these. The
|
|
following relationships might be useful:<br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> <span style="font-family: monospace;">P
|
|
= sqrt(a*a*a)<br>
|
|
p = O + o<br>
|
|
n = 0.9856076686/P<br>
|
|
T = E - M/n<br>
|
|
q = a*(1-e)</span><br>
|
|
AU = 149,597,870 km = 92,955,621 U.S. statute miles<br>
|
|
<br>
|
|
where<br>
|
|
<br>
|
|
<span style="font-family: monospace;">P</span> = the orbital period,
|
|
years;<br>
|
|
<span style="font-family: monospace;">p</span> = longitude of
|
|
perihelion, degrees<br>
|
|
<span style="font-family: monospace;">T</span> = epoch of perihelion
|
|
(add multiples of P for desired range)<br>
|
|
<span style="font-family: monospace;">q</span> = perihelion distance, AU<br>
|
|
<br>
|
|
Note that if you know T you can then set E = T and M = 0. </div>
|
|
</div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> If <span style="font-weight: bold;">Field
|
|
2</span> is <span style="font-weight: bold;">h</span> the object type
|
|
is
|
|
hyperbolic heliocentric (eccentricity > 1) and the remaining fields
|
|
are defined as follows:<br>
|
|
<br>
|
|
<div style="margin-left: 40px;">
|
|
<table style="text-align: left; width: 95%;" summary="hyperbolic fields"
|
|
border="0" cellpadding="2" cellspacing="2">
|
|
<tbody>
|
|
<tr>
|
|
<td style="vertical-align: top; font-weight: bold; width: 100px;">Field
|
|
3<br>
|
|
</td>
|
|
<td colspan="2" rowspan="1" style="vertical-align: top;">T = date
|
|
of the epoch of perihelion</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top;"><br>
|
|
</td>
|
|
<td style="vertical-align: top; width: 100px;"><b>SubField 3A</b></td>
|
|
<td style="vertical-align: top;">First date these elements are
|
|
valid, optional</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top;"><br>
|
|
</td>
|
|
<td style="vertical-align: top; width: 100px;"><b>SubField 3B</b></td>
|
|
<td style="vertical-align: top;">Last date these elements are
|
|
valid, optional</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-weight: bold; width: 100px;">Field
|
|
4<br>
|
|
</td>
|
|
<td colspan="2" rowspan="1" style="vertical-align: top;">i =
|
|
inclination of orbital plane to ecliptic, degrees</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-weight: bold; width: 100px;">Field
|
|
5<br>
|
|
</td>
|
|
<td colspan="2" rowspan="1" style="vertical-align: top;">O =
|
|
longitude of ascending node, degrees</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-weight: bold; width: 100px;">Field
|
|
6<br>
|
|
</td>
|
|
<td colspan="2" rowspan="1" style="vertical-align: top;">o =
|
|
argument of perihelion, degrees</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-weight: bold; width: 100px;">Field
|
|
7<br>
|
|
</td>
|
|
<td colspan="2" rowspan="1" style="vertical-align: top;">e =
|
|
eccentricity, must be > 1<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-weight: bold; width: 100px;">Field
|
|
8<br>
|
|
</td>
|
|
<td colspan="2" rowspan="1" style="vertical-align: top;">q =
|
|
perihelion distance, AU</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-weight: bold; width: 100px;">Field
|
|
9<br>
|
|
</td>
|
|
<td colspan="2" rowspan="1" style="vertical-align: top;">D = the
|
|
equinox year (i.e., time of i/O/o)</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-weight: bold; width: 100px;">Field
|
|
10<br>
|
|
</td>
|
|
<td colspan="2" rowspan="1" style="vertical-align: top;">g
|
|
component of magnitude model. See <a href="#mag_models">Magnitude
|
|
models</a>.</td>
|
|
</tr>
|
|
<tr>
|
|
<td valign="top"><b>Field 11</b><br>
|
|
</td>
|
|
<td colspan="2" rowspan="1" valign="top">k component of magnitude
|
|
model<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-weight: bold; width: 100px;">Field
|
|
12<br>
|
|
</td>
|
|
<td colspan="2" rowspan="1" style="vertical-align: top;">s =
|
|
angular size at 1 AU, arc seconds, optional</td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
</div>
|
|
</div>
|
|
<div style="margin-left: 120px;"></div>
|
|
<br>
|
|
<div style="margin-left: 80px;"> As with elliptical elements, other
|
|
parameters might be available. The relationships are generally the
|
|
same, except: </div>
|
|
<br>
|
|
<div style="margin-left: 40px;">
|
|
<div style="margin-left: 80px;"> <span style="font-family: monospace;">q
|
|
= a*(e-1)</span> </div>
|
|
<br>
|
|
If <span style="font-weight: bold;">Field 2</span> is <span
|
|
style="font-weight: bold;">p</span> the object type is parabolic
|
|
heliocentric (eccentricity exactly equal to 1) and the remaining
|
|
fields are defined as follows:<br>
|
|
<br>
|
|
<table style="text-align: left; width: 95%; margin-left: 40px;"
|
|
summary="parabolic fields" border="0" cellpadding="2" cellspacing="2">
|
|
<tbody>
|
|
<tr>
|
|
<td style="vertical-align: top; font-weight: bold; width: 100px;">Field
|
|
3<br>
|
|
</td>
|
|
<td colspan="2" rowspan="1" style="vertical-align: top;">T = date
|
|
of epoch of perihelion</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top;"><br>
|
|
</td>
|
|
<td style="vertical-align: top; width: 100px;"><b>SubField 3A</b></td>
|
|
<td style="vertical-align: top;">First date these elements are
|
|
valid, optional</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top;"><br>
|
|
</td>
|
|
<td style="vertical-align: top; width: 100px;"><b>SubField 3B</b></td>
|
|
<td style="vertical-align: top;">Last date these elements are
|
|
valid, optional</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-weight: bold; width: 100px;">Field
|
|
4<br>
|
|
</td>
|
|
<td colspan="2" rowspan="1" style="vertical-align: top;">i =
|
|
inclination, degrees</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-weight: bold; width: 100px;">Field
|
|
5<br>
|
|
</td>
|
|
<td colspan="2" rowspan="1" style="vertical-align: top;">o =
|
|
argument of perihelion, degrees</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-weight: bold; width: 100px;">Field
|
|
6<br>
|
|
</td>
|
|
<td colspan="2" rowspan="1" style="vertical-align: top;">q =
|
|
perihelion distance, AU</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-weight: bold; width: 100px;">Field
|
|
7<br>
|
|
</td>
|
|
<td colspan="2" style="vertical-align: top;">O = longitude of
|
|
ascending node, degrees</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-weight: bold; width: 100px;">Field
|
|
8<br>
|
|
</td>
|
|
<td colspan="2" style="vertical-align: top;">D = the equinox year
|
|
(i.e., time of i/O/o).</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-weight: bold; width: 100px;">Field
|
|
9<br>
|
|
</td>
|
|
<td colspan="2" style="vertical-align: top;">g component of
|
|
magnitude model. See <a href="#mag_models">Magnitude models</a>.</td>
|
|
</tr>
|
|
<tr>
|
|
<td valign="top"><b>Field 10</b><br>
|
|
</td>
|
|
<td colspan="2" rowspan="1" valign="top">k component of magnitude
|
|
model</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-weight: bold; width: 100px;">Field
|
|
11<br>
|
|
</td>
|
|
<td colspan="2" style="vertical-align: top;">s = angular size at
|
|
1 AU, arc seconds, optional</td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
</div>
|
|
<div style="margin-left: 80px;"></div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> If <span style="font-weight: bold;">Field
|
|
2</span> is <span style="font-weight: bold;">E</span> (note upper
|
|
case)
|
|
the object type is Earth satellite and the remaining fields are defined
|
|
as follows:<br>
|
|
<br>
|
|
<br>
|
|
<table style="text-align: left; width: 95%; margin-left: 40px;"
|
|
summary="earth sat fields" border="0" cellpadding="2" cellspacing="2">
|
|
<tbody>
|
|
<tr>
|
|
<td style="vertical-align: top; font-weight: bold; width: 100px;">Field
|
|
3<br>
|
|
</td>
|
|
<td colspan="2" style="vertical-align: top;">Epoch of the other
|
|
fields</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top;"><br>
|
|
</td>
|
|
<td style="vertical-align: top; width: 100px;"><b>SubField 3A</b></td>
|
|
<td style="vertical-align: top;">First date these elements are
|
|
valid, optional</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top;"><br>
|
|
</td>
|
|
<td style="vertical-align: top; width: 100px;"><b>SubField 3B<br>
|
|
</b></td>
|
|
<td style="vertical-align: top;">Last date these elements are
|
|
valid, optional</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-weight: bold; width: 100px;">Field
|
|
4<br>
|
|
</td>
|
|
<td colspan="2" style="vertical-align: top;">inclination, degrees</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-weight: bold; width: 100px;">Field
|
|
5<br>
|
|
</td>
|
|
<td colspan="2" style="vertical-align: top;">RA of ascending
|
|
node, degrees</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-weight: bold; width: 100px;">Field
|
|
6<br>
|
|
</td>
|
|
<td colspan="2" style="vertical-align: top;">eccentricity, must
|
|
be < 1</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-weight: bold; width: 100px;">Field
|
|
7<br>
|
|
</td>
|
|
<td colspan="2" style="vertical-align: top;">argument of perigee,
|
|
degrees</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-weight: bold; width: 100px;">Field
|
|
8<br>
|
|
</td>
|
|
<td colspan="2" style="vertical-align: top;">mean anomaly, degrees</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-weight: bold; width: 100px;">Field
|
|
9<br>
|
|
</td>
|
|
<td colspan="2" style="vertical-align: top;">mean motion, revs/day</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-weight: bold; width: 100px;">Field
|
|
10<br>
|
|
</td>
|
|
<td colspan="2" style="vertical-align: top;">orbit decay rate,
|
|
revolutions/day^2</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-weight: bold; width: 100px;">Field
|
|
11<br>
|
|
</td>
|
|
<td colspan="2" style="vertical-align: top;">integral reference
|
|
orbit number at Epoch<br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-weight: bold; width: 100px;">Field
|
|
12<br>
|
|
</td>
|
|
<td colspan="2" style="vertical-align: top;">drag coefficient,
|
|
1/(earth radii); optional</td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
</div>
|
|
<br>
|
|
<div style="margin-left: 80px;"> XEphem arbitrarily assigns all Earth
|
|
satellites a visual magnitude of 2.0.<br>
|
|
<br>
|
|
XEphem can also read files directly containing the venerable
|
|
Two-Line-Element (TLE) format. See next section for details.
|
|
<br>
|
|
<br>
|
|
If not specified explicitly in the edb entry, XEphem assigns the valid range
|
|
of dates for satellite elements to the greater of 100 days or the time
|
|
required for the mean motion to change by one percent either side of the
|
|
element epoch.
|
|
</div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> If <span style="font-weight: bold;">Field
|
|
2</span> is <span style="font-weight: bold;">P</span> (note upper
|
|
case)
|
|
then <span style="font-weight: bold;">Field 1</span> must be the name
|
|
of
|
|
a built-in object for XEphem and no other fields are defined. The
|
|
following names are recognized:<br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Sun<br>
|
|
Moon<br>
|
|
Mercury<br>
|
|
Venus<br>
|
|
Mars<br>
|
|
<div style="margin-left: 40px;"> Phobos<br>
|
|
Deimos </div>
|
|
Jupiter<br>
|
|
<div style="margin-left: 40px;"> Io </div>
|
|
<div style="margin-left: 40px;"> Europa<br>
|
|
Ganymede<br>
|
|
Callisto </div>
|
|
Saturn<br>
|
|
<div style="margin-left: 40px;"> Mimas<br>
|
|
Enceladus<br>
|
|
Tethys<br>
|
|
Dione<br>
|
|
Rhea<br>
|
|
Titan<br>
|
|
Hyperion<br>
|
|
Iapetus </div>
|
|
Uranus<br>
|
|
<div style="margin-left: 40px;"> Ariel<br>
|
|
Umbriel<br>
|
|
Titania<br>
|
|
Oberon<br>
|
|
Miranda </div>
|
|
Neptune<br>
|
|
Pluto </div>
|
|
</div>
|
|
<h4><a class="mozTocH4" name="mozTocId564354"></a> 7.1.2.3 <span
|
|
style="font-weight: bold;"><a name="mag_models"></a>Magnitude models</span></h4>
|
|
The <span style="font-weight: bold;">g,k</span> magnitude model
|
|
requires two parameters to be specified. One, the absolute magnitude,
|
|
g, is the visual magnitude of the object if it were one AU from both
|
|
the Sun and the Earth. The other, the luminosity index, k,
|
|
characterizes the brightness change of the object as a function of its
|
|
distance from the Sun. This is generally zero, or very small, for
|
|
inactive objects like asteroids. The model may be expressed as:<br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> <span style="font-family: monospace;">m
|
|
= g + 5*log10(D) + 2.5*k*log10(r)</span> </div>
|
|
<br>
|
|
where:<br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> <span style="font-family: monospace;">m</span>
|
|
= resulting visual magnitude<br>
|
|
<span style="font-family: monospace;">g</span> = absolute visual
|
|
magnitude<br>
|
|
<span style="font-family: monospace;">D</span> = comet-earth distance,
|
|
in AU </div>
|
|
<div style="margin-left: 40px;"> <span style="font-family: monospace;">k</span>
|
|
= luminosity index </div>
|
|
<div style="margin-left: 40px;"> <span style="font-family: monospace;">r</span>
|
|
= comet-sun distance. </div>
|
|
<br>
|
|
The <span style="font-weight: bold;">H,G</span> model also requires
|
|
two parameters. The first, H, is the magnitude of the object when one
|
|
AU from the Sun and the Earth. The other, G, attempts to model the
|
|
reflection characteristics of a passive surface, such as an asteroid.
|
|
The model may be expressed with the following code fragment:<br>
|
|
<br style="font-family: monospace;">
|
|
<div style="margin-left: 40px;"> <span style="font-family: monospace;">beta
|
|
= acos((rp*rp + rho*rho - rsn*rsn)/ (2*rp*rho));</span><br
|
|
style="font-family: monospace;">
|
|
<span style="font-family: monospace;">psi_t =
|
|
exp(log(tan(beta/2.0))*0.63);</span><br style="font-family: monospace;">
|
|
<span style="font-family: monospace;">Psi_1 = exp(-3.33*psi_t);</span><br
|
|
style="font-family: monospace;">
|
|
<span style="font-family: monospace;">psi_t =
|
|
exp(log(tan(beta/2.0))*1.22);</span><br style="font-family: monospace;">
|
|
<span style="font-family: monospace;">Psi_2 = exp(-1.87*psi_t);</span><br
|
|
style="font-family: monospace;">
|
|
<span style="font-family: monospace;">m = H + 5.0*log10(rp*rho) -
|
|
2.5*log10((1-G)*Psi_1 + G*Psi_2);</span> </div>
|
|
<br>
|
|
where:<br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> <span style="font-family: monospace;">m </span>=
|
|
resulting visual magnitude<br>
|
|
<span style="font-family: monospace;">rp </span>= distance from
|
|
sun to object<br>
|
|
<span style="font-family: monospace;">rho </span>= distance from
|
|
earth to object<br>
|
|
<span style="font-family: monospace;">rsn </span>= distance from
|
|
sun to earth </div>
|
|
<br>
|
|
Note that neither model takes into account the phase angle of sun light.<br>
|
|
<br>
|
|
<blockquote> <a name="Database_notes"></a> </blockquote>
|
|
<h3><a class="mozTocH3" name="mozTocId184653"></a> 7.1.3 Notes</h3>
|
|
<p>XEphem uses a different window to manage <a href="#FieldStars">Field
|
|
star</a> catalogs.</p>
|
|
<p>XEphem ships with a few perl scripts which might be helpful for
|
|
converting databases in other formats into XEphem format. These
|
|
scripts are in the tools/ directory of the source distribution tree.<br>
|
|
</p>
|
|
<h3><a class="mozTocH3" name="mozTocId74433"></a> 7.1.4 Two-line Earth
|
|
satellite element sets</h3>
|
|
XEphem supports reading files which contain Earth satellites defined
|
|
using the the NORAD "two-line element" set format, or TLE. Because the
|
|
TLE format is quite rigid and includes a checksum within each line,
|
|
XEphem is able to search files containing other arbitrary text and find
|
|
each properly formatted TLE contained therein. Follows is a description
|
|
of the TLE. Note the line immediately preceding the TLE, line "0", is
|
|
assumed to contain a common name for the satellite, this line is only
|
|
used if the following two lines conform to TLE.<br>
|
|
<br>
|
|
Data for each satellite consists of three lines in the following
|
|
format:
|
|
<pre>AAAAAAAAAAAAAAAAAAAAAAAA<br>1 NNNNNU NNNNNAAA NNNNN.NNNNNNNN +.NNNNNNNN +NNNNN-N +NNNNN-N N NNNNN<br>2 NNNNN NNN.NNNN NNN.NNNN NNNNNNN NNN.NNNN NNN.NNNN NN.NNNNNNNNNNNNNN<br></pre>
|
|
<p>Line 0 is a twenty-four character name.<br>
|
|
</p>
|
|
<p>Lines 1 and 2 are the standard Two-Line Orbital Element Set Format
|
|
identical to that
|
|
used by NORAD and NASA. The format description is:<br>
|
|
</p>
|
|
<div align="left"></div>
|
|
<table border="0" cellpadding="2" cellspacing="2">
|
|
<tbody>
|
|
<tr>
|
|
<th colspan="2" align="center">Line 1</th>
|
|
</tr>
|
|
<tr>
|
|
<th width="75">Column</th>
|
|
<th width="500">Description</th>
|
|
</tr>
|
|
<tr>
|
|
<td align="center">01</td>
|
|
<td>Line Number of Element Data</td>
|
|
</tr>
|
|
<tr>
|
|
<td align="center">03-07</td>
|
|
<td>Satellite Number</td>
|
|
</tr>
|
|
<tr>
|
|
<td align="center">08</td>
|
|
<td>Classification (U=Unclassified)</td>
|
|
</tr>
|
|
<tr>
|
|
<td align="center">10-11</td>
|
|
<td>International Designator, last two digits of launch
|
|
year, 2000+ if < 57.</td>
|
|
</tr>
|
|
<tr>
|
|
<td align="center">12-14</td>
|
|
<td>International Designator, launch number of the year</td>
|
|
</tr>
|
|
<tr>
|
|
<td align="center">15-17</td>
|
|
<td>International Designator, piece of the launch</td>
|
|
</tr>
|
|
<tr>
|
|
<td align="center">19-20</td>
|
|
<td>Epoch Year, last two digits of year, 2000+ if < 57</td>
|
|
</tr>
|
|
<tr>
|
|
<td align="center">21-32</td>
|
|
<td>Epoch Day of the year and fractional portion of the day</td>
|
|
</tr>
|
|
<tr>
|
|
<td align="center">34-43</td>
|
|
<td>First Time Derivative of the Mean Motion</td>
|
|
</tr>
|
|
<tr>
|
|
<td align="center">45-52</td>
|
|
<td>Second Time Derivative of Mean Motion (decimal point assumed)</td>
|
|
</tr>
|
|
<tr>
|
|
<td align="center">54-61</td>
|
|
<td>BSTAR drag term (decimal point assumed)</td>
|
|
</tr>
|
|
<tr>
|
|
<td align="center">63</td>
|
|
<td>Ephemeris type</td>
|
|
</tr>
|
|
<tr>
|
|
<td align="center">65-68</td>
|
|
<td>Element number</td>
|
|
</tr>
|
|
<tr>
|
|
<td align="center">69</td>
|
|
<td>Checksum (Modulo 10)<br>
|
|
<div align="left"> (Letters, blanks, periods, plus signs = 0;
|
|
minus signs = 1)</div>
|
|
</td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
<br>
|
|
<br>
|
|
<table border="0" cellpadding="2" cellspacing="2">
|
|
<tbody>
|
|
<tr>
|
|
<th colspan="2">Line 2</th>
|
|
</tr>
|
|
<tr>
|
|
<th width="75">Column</th>
|
|
<th width="500">Description</th>
|
|
</tr>
|
|
<tr>
|
|
<td align="center">01</td>
|
|
<td>Line Number of Element Data</td>
|
|
</tr>
|
|
<tr>
|
|
<td align="center">03-07</td>
|
|
<td>Satellite Number</td>
|
|
</tr>
|
|
<tr>
|
|
<td align="center">09-16</td>
|
|
<td>Inclination [Degrees]</td>
|
|
</tr>
|
|
<tr>
|
|
<td align="center">18-25</td>
|
|
<td>Right Ascension of the Ascending Node [Degrees]</td>
|
|
</tr>
|
|
<tr>
|
|
<td align="center">27-33</td>
|
|
<td>Eccentricity (decimal point assumed)</td>
|
|
</tr>
|
|
<tr>
|
|
<td align="center">35-42</td>
|
|
<td>Argument of Perigee [Degrees]</td>
|
|
</tr>
|
|
<tr>
|
|
<td align="center">44-51</td>
|
|
<td>Mean Anomaly [Degrees]</td>
|
|
</tr>
|
|
<tr>
|
|
<td align="center">53-63</td>
|
|
<td>Mean Motion [Revs per day]</td>
|
|
</tr>
|
|
<tr>
|
|
<td align="center">64-68</td>
|
|
<td>Revolution number at epoch [Revs]</td>
|
|
</tr>
|
|
<tr>
|
|
<td align="center">69</td>
|
|
<td>Checksum (Modulo 10)</td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
<br>
|
|
<p>
|
|
When reading a TLE entry, XEphem assigns the valid range of dates for a set of
|
|
elements to the greater of 100 days or the time required for the mean motion
|
|
to change by one percent either side of the element epoch.
|
|
|
|
<br>
|
|
<a name="Object"></a>
|
|
<h2><a class="mozTocH1" name="mozTocId396689"></a> 7.2 Index</h2>
|
|
<img alt="" src="png/data-index.png" align="right" height="433"
|
|
hspace="10" vspace="10" width="437">This
|
|
window shows a list of all objects currently loaded into memory sorted
|
|
by name. Or, by chosing a toggle button across the top, the list can
|
|
be restricted to just deep sky, stellar, binary systems, solar system
|
|
and
|
|
Earth
|
|
satellites. The list does not include Favorites.<br>
|
|
<br>
|
|
Each object name, including all alternate names, are in the scrolled
|
|
list on
|
|
the right. Clicking an arrow
|
|
button moves the list by one object up or down; clicking above or below
|
|
the thumb
|
|
control scrolls the list so that the top object moves to the bottom or <span
|
|
style="font-style: italic;">visa versa</span>. Clicking on an object
|
|
displays its defining parameters in the box to the left, and also
|
|
displays its .edb file format entry in the read-only text field below.<br>
|
|
<br>
|
|
The list of objects may be searched by entering a <a
|
|
href="xephem.html#glob">glob</a> pattern in the <span
|
|
style="font-weight: bold;">Search</span> field then
|
|
typing Enter or clicking Search. If more than one object name matches,
|
|
clicking Search again scrolls to the next candidate; the search wraps
|
|
back to the front when no more are found.<br>
|
|
<br>
|
|
Buttons across the bottom function as follows:<br>
|
|
<br>
|
|
<span style="font-weight: bold;">Sky Point</span><br>
|
|
<div style="margin-left: 40px;"> <br>
|
|
This will mark the object currently selected in the <a href="#SkyView">Sky
|
|
View</a>, repointing if necessary to move it into the field of
|
|
view.<br>
|
|
<br>
|
|
</div>
|
|
<span style="font-weight: bold;">Show in Gallery<br>
|
|
<br>
|
|
</span>
|
|
<div style="margin-left: 40px;">If this object is in the <a
|
|
href="#Gallery">Gallery</a>, this button will be available and will
|
|
display the object. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Save as Favorite<br>
|
|
<br>
|
|
</span>
|
|
<div style="margin-left: 40px;"> This button will add the object
|
|
currently
|
|
selected to the list of <a href="#Favorites">Favorites</a>. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Tel Goto<br>
|
|
<br>
|
|
</span>
|
|
<div style="margin-left: 40px;"> This will send the object currently
|
|
selected to the <a href="#SkyView_telescope">Telescope</a> control
|
|
system. Whether this button is active depends on the state of the
|
|
telescope control subsystem when the Index window was opened. If the
|
|
button state is incorrect, close and reopen the Index window.<br
|
|
clear="all">
|
|
</div>
|
|
<a name="Favorites"></a>
|
|
<h2><a class="mozTocH1" name="mozTocId156306"></a> 7.3 Favorites</h2>
|
|
<img alt="" src="png/favorites.png" align="right" height="448"
|
|
hspace="10" width="219">This
|
|
window allows you to add, arrange, remove and temporarily deactivate an
|
|
arbitrary collection
|
|
of XEphem objects, called Favorites. Once defined as a Favorite, the
|
|
object remains available whether or not its original <a
|
|
href="#Database">database file</a> is currently loaded. <br>
|
|
<br>
|
|
Favorites have special significance in several places throughout
|
|
XEphem. For example the rows in the <a href="#Data_Table">Data Table</a>
|
|
and in the <a href="#NightAtAGlance">Night at a Glance</a> windows are
|
|
exactly those of the Favorites. The <a href="#Earth">Earth</a> view
|
|
shows those Favorites which are satellites. Favorites are available
|
|
very
|
|
easily in the Favorites menu in the <a href="#SkyView">Sky View</a>.
|
|
And the <a href="#Solsys">Solar System</a> view displays those
|
|
Favorites
|
|
that are within the solar system.<br>
|
|
<br>
|
|
Objects may be added to the list of Favorites in several ways:<br>
|
|
<ul>
|
|
<li>from the <span style="font-family: monospace;"><a href="#Object">Data
|
|
</a></span><a href="#Object"><span style="font-family: monospace;">»
|
|
</span></a><span style="font-family: monospace;"><a href="#Object">Index</a></span>
|
|
window by browsing the objects currently loaded in memory then clicking
|
|
<b>Favorite</b>;</li>
|
|
<li>from buttons labeled <b>Favorite</b> located in several dialogs
|
|
throughout XEphem;<br>
|
|
</li>
|
|
<li>from buttons in the popup menus of several views when clicked
|
|
over displayed objects; and<br>
|
|
</li>
|
|
<li>by entering its .edb format definition in the text field near the
|
|
bottom of the Favorites window and clicking <b>Add edb</b>.<br>
|
|
Note this field may also be used to edit an existing Favorite in-place.
|
|
</li>
|
|
</ul>
|
|
Each entry in the Favorites list shows its complete .edb format
|
|
definition. Each entry has the following controls:<br>
|
|
<blockquote><span style="font-weight: bold;">Del</span><br>
|
|
<div style="margin-left: 40px;">removes the entry from the Favorites
|
|
list<br>
|
|
</div>
|
|
<span style="font-weight: bold;"></span><br>
|
|
<span style="font-weight: bold;">Up and Down arrow buttons</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;">move the entry up and down to arrange
|
|
the Favorites into any designed order. This is useful where Favorites
|
|
define rows such as in the <a href="#Data_Table">Data Table</a> and <a
|
|
href="#NightAtAGlance">Night at a Glance</a> windows.<br>
|
|
<br>
|
|
</div>
|
|
<span style="font-weight: bold;">Use</span><br>
|
|
<span style="font-weight: bold;"></span><br>
|
|
<span style="font-weight: bold;"></span>
|
|
<div style="margin-left: 40px;">specifies whether to use or hide the
|
|
entry from
|
|
the rest of XEphem without actually Deleting it. </div>
|
|
</blockquote>
|
|
The buttons across the bottom allow you to <b>Save</b> the current set
|
|
of Favorites to a file and later <b>Load</b> them again.
|
|
The suffix of these files must be <b>.fav</b> and will be added
|
|
automatically if not included in the file named in the text field. When
|
|
XEphem first starts, it automatically
|
|
loads the file named in the Save text field. To save this file name, go
|
|
to <span style="font-family: monospace;">Preferences » Save</span>
|
|
and <a href="#Save">Save</a>
|
|
the XEphem*Favorites*File resource under the Favorites category.<br>
|
|
<br>
|
|
<br>
|
|
<a name="WebDB"></a>
|
|
<h2><a class="mozTocH1" name="mozTocId69192"></a> 7.4 Download<br>
|
|
</h2>
|
|
<img style="width: 496px; height: 284px;" alt="" title=""
|
|
src="png/internet-update.png" align="right" hspace="20"> This
|
|
window provides an easy means to download from the Internet to disk and
|
|
simultaneously
|
|
load into memory any file which contains objects defined in either
|
|
XEphem's .edb format or the NORAD 2-Line Element (TLE) format commonly
|
|
used for Earth satellite. The file is saved in the <a
|
|
href="#SharedPrivateDirs">Private</a> directory, converted to .edb
|
|
format if it is not already.<br>
|
|
<br>
|
|
Several particularly useful sites as of this build are already entered.
|
|
The first three are from Dr. TS Kelso's Earth satellite lists at <a
|
|
href="http://www.celestrak.com">celestrak.com</a>. The other four are
|
|
the Minor Planet Center's lists of hot comets and unusual asteroids
|
|
specially formatted for <a
|
|
href="http://cfa-www.harvard.edu/iau/Ephemerides/Soft03.html">XEphem</a>.
|
|
Click <span style="font-weight: bold;">Get</span> beside the desired
|
|
catalog to download the file to the Private directory and
|
|
simultaneously load into XEphem memory.<br>
|
|
<br>
|
|
Special files created by the <a
|
|
href="http://cfa-www.harvard.edu/cfa/ps/mpc.html">Minor Planet Center</a>
|
|
and <a href="ftp://ftp.lowell.edu/pub/elgb/astorb.html">Lowell
|
|
Observatory</a> may also be downloaded. Each organization maintains
|
|
extensive lists of all known asteroids and produces on a regular basis
|
|
Keplarian orbital elements precessed to the current date. Both are of
|
|
excellent quality. When the <span style="font-weight: bold;">Get</span>
|
|
button is clicked, XEphem downloads the appropriate file, uncompresses
|
|
it, reformats it to .edb format and splits the results into two files
|
|
for convenience. One file will contain all asteroids which can ever
|
|
become brighter than magnitude 13, and the other (with a "_dim" suffix)
|
|
contains all the rest. All files are created in the user's Private
|
|
XEphem directory. The real work is performed by two perl scripts,
|
|
mpcorb.pl and astorb.pl, respectively. These may be run independently
|
|
of XEphem if desired.<br clear="all">
|
|
<br>
|
|
<br>
|
|
<a name="FieldStars"></a>
|
|
<h2><a class="mozTocH1" name="mozTocId147305"></a> 7.5 Field Stars</h2>
|
|
<img alt="" src="png/fieldstars.png" align="right" height="345"
|
|
hspace="10" vspace="10" width="546">This window allows you to control
|
|
which
|
|
field star
|
|
sources you wish to use. The window is accessible from the Main window
|
|
as well as from the Control menus of most graphical views.<br>
|
|
<br>
|
|
XEphem uses the term "field star" to refer to the huge numbers of faint
|
|
stars visible in any real world view of the sky. Field stars are
|
|
generally far more numerous than could be reasonably accommodated in
|
|
the XEphem *.edb database format. For this reason they are stored and
|
|
made available in their own special compact forms for utmost
|
|
efficiency. The downside to this approach is that field stars are not
|
|
included in the totals presented by the <span
|
|
style="font-family: monospace;">Data » Files</span> window nor
|
|
are they available for searching or inspection using the <span
|
|
style="font-family: monospace;">Data » Index</span> window.
|
|
This results in little loss of generality, however, since (once
|
|
found!) they may be assigned to the user Favorites.<br>
|
|
<br>
|
|
The controls in the Field Stars setup window are grouped into
|
|
categories, depending on the basic source of the stars, as follows:<br>
|
|
<br>
|
|
<h3><a class="mozTocH3" name="mozTocId160208"></a> 7.5.1 <span
|
|
style="font-weight: bold;">Hubble GSC</span></h3>
|
|
The Hubble Guide Star Catalog is a seminal work created by the Space
|
|
Telescope Science Institute to support the Hubble Space telescope. It
|
|
contains from 13 million unique stars, or about 300 stars per square
|
|
degree of sky.<br>
|
|
<br>
|
|
<span style="font-weight: bold;">ASP CDROM Directory<br>
|
|
<br>
|
|
</span>
|
|
<div style="margin-left: 40px;">This choice enables reading field stars
|
|
from the Hubble Guide Star Catalog made available some years ago
|
|
on two CDROMs published by the Astronomical Society of the
|
|
Pacific. Mount a CDROM somewhere onto your filesystem, type the
|
|
name of the mount directory in the text field provided then turn
|
|
this option on and press Apply. Note that XEphem assumes your CDROM
|
|
driver removes the trailing ";1" from all filenames.<br>
|
|
</div>
|
|
<br>
|
|
<span style="font-weight: bold;">Local Cache Directory</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;">This choice enables reading GSC field
|
|
stars from your local disk. If this option is on along with the
|
|
CDROM option, then as requests are satisfied from the CDROM a
|
|
compact form of the same data will be written to files below the
|
|
directory named in this option. Then the next time the same field stars
|
|
are needed, and this option is on, they will be obtained from the
|
|
local disk files rather than the CDROM. In fact, the CDROM is not
|
|
needed
|
|
or used if the local disk contains all the stars for any given
|
|
access. The entire 2 CDROM set loads onto disk in this format in
|
|
some 180 MB. The default path of the directory which holds the
|
|
disk version is "catalogs/gsc" off the Shared directory. Note:
|
|
There is also a utility in the tools/gsc directory, gscload, with
|
|
which you may preload any entire CDROM segment at once if desired.
|
|
These files are already included in te commercial version of
|
|
XEphem.<span style="font-weight: bold;"></span><br>
|
|
<span style="font-weight: bold;"></span></div>
|
|
<span style="font-weight: bold;"><br>
|
|
Internet to xephemdbd<br>
|
|
<br>
|
|
</span>
|
|
<div style="margin-left: 40px;">This choice is to use the Internet to
|
|
access an XEphem GSC server. To use this source, select this
|
|
option and type the URL to the remote xephemdbd.pl in the text
|
|
field provided.<br>
|
|
</div>
|
|
<span style="font-weight: bold;"><br>
|
|
GSC 2.2 Directory<br>
|
|
<br>
|
|
</span>
|
|
<div style="margin-left: 40px;">This choice enables using a local copy
|
|
of the GSC 2.2.0.1 catalog in xe3 format. This catalog only contains
|
|
stars between magnitude 10 and 18.5, so it must be used in conjunction
|
|
with
|
|
an additional catalog for completeness. The Hipparcos catalog is an
|
|
ideal companion and is automatically chosen as a convenience.
|
|
<br>
|
|
</div>
|
|
<br>
|
|
<span style="font-weight: bold;"></span><span style="font-weight: bold;"></span>
|
|
<h3><a class="mozTocH3" name="mozTocId676533"></a> 7.5.2 <span
|
|
style="font-weight: bold;">USNO A or SA catalogs</span></h3>
|
|
<br>
|
|
<span style="font-weight: bold;">Root directory</span><br>
|
|
<div style="margin-left: 40px;"> <br>
|
|
This choice of field stars supports the SA and the A series of
|
|
astrometric catalogs produced by the US Naval Observatory. The SA2.0
|
|
for example, includes some 54 million stars, about a tenth of the parent A2.0,
|
|
spatially sampled so there is about 1,300 stars per square degree of
|
|
sky. Note that such a uniform distribution does not "look" much like
|
|
the real sky, but it is great for its intended use as an astrometric
|
|
mesh for comet hunters or such. If you have such a catalog, simply
|
|
enter the name of its base directory and toggle this switch on.
|
|
The default assumes a symbolic link, "catalogs/usno" off the shared
|
|
directory. Multiple versions of the catalogs can be stored, each in
|
|
its own directory, but only one may be active at a time.<br>
|
|
<br>
|
|
The suggested citation for SA2.0 follows:<br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Monet, D., Bird, A., Canzian, B.,
|
|
Dahn, C., Guetter, H., Harris, H., Henden, A., Levine, S., Luginbuhl, C.,
|
|
Monet, A., Rhodes, A., Riepe, B., Sell, S., Stone, R., Vrba, F., Walker, R.,
|
|
1998, USNO-SA2.0, (U.S. Naval Observatory, Washington DC). </div>
|
|
<br>
|
|
This catalog has been included with permission of USNO as long as
|
|
we mention the following stipulations:<br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> It may not be the latest version,
|
|
check with http://www.usno.navy.mil. </div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> If you paid for XEphem, you paid for
|
|
the software, not this catalog. The catalog is available free from
|
|
the USNO. </div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Inclusion of the SA2.0 catalog does
|
|
not imply an endorsement of XEphem by USNO; nor was there privileged
|
|
access to the catalog; nor does the US Government affirm or
|
|
guarantee that XEphem works properly in any way. </div>
|
|
</div>
|
|
<span style="font-weight: bold;"><br>
|
|
</span>
|
|
<h3><a class="mozTocH3" name="mozTocId619625"></a> 7.5.3 <span
|
|
style="font-weight: bold;">Proper Motion catalogs</span></h3>
|
|
<br>
|
|
These large catalogs include information regarding proper motion.
|
|
Two such catalogs are currently available ready for XEphem. You may
|
|
only use one at a time, by choosing the corresponding toggle<span
|
|
style="font-weight: bold;"><br>
|
|
<br>
|
|
PPM catalog</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;">This is the Positions and Proper Motion
|
|
catalog of S. Roeser and U. Bastian, Astronomisches
|
|
Rechen-Institut, Heidelberg, published in 1990. The PPM includes
|
|
468,586 stars rather evenly distributed throughout both
|
|
hemispheres. This averages out to more than 10 stars per square
|
|
degree. The set here includes the original North and South
|
|
editions plus the extended supplement. The set includes more than
|
|
99% of the stars in the original SAO catalog and some 70% of the
|
|
Henry Draper Catalogue (HD). While the SAO catalog is more or less
|
|
complete to V=9, with stars as faint as V=10, the PPM catalog is
|
|
fairly complete to V=9.5, and goes somewhat deeper than V=10.<br>
|
|
</div>
|
|
<br>
|
|
<span style="font-weight: bold;">Hipparcos and Tycho-2</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;">This catalog is a combination of the
|
|
Hipparcos and the Tycho-2 astrometric catalogs published by the
|
|
European Space Agency. This catalog contains all Hipparcos stars
|
|
for which astrometric and magnitude values are assigned, and all
|
|
additional non-redundant entries from the Tycho-2 catalog except
|
|
multiple-component entries. There is a total of some 2.5 million
|
|
stars, or about 60 stars per square degree. One example of a star with
|
|
high proper motion is Groombridge 1830 (HD 103095), in Ursa Major,
|
|
near 11h53m 37d44m. For a nice discussion see Burnham's Celestial
|
|
Handbook, Volume III, page 1978. By comparing its position in either
|
|
PM catalog with the same entry from the GSC one can deduce this
|
|
particular GSC field was evidently taken in early 1983.<br>
|
|
</div>
|
|
<span style="font-weight: bold;">
|
|
<br>
|
|
UCAC</span>
|
|
<div style="margin-left: 40px;"><br>
|
|
This choice allows using the USNO Astrographic catalog with XEphem. For
|
|
more information on this catalog please refer to
|
|
<a target="_blank" href="http://www.usno.navy.mil/USNO/astrometry/optical-IR-prod/ucac">here</a>.
|
|
As of release UCAC4, the directory specified must be that which contains
|
|
the u4b and u4i directories. In turn, u4b must contain all 900 z files and
|
|
u4i must contain u4index.unf and u4hpm.dat.
|
|
<br>
|
|
</div>
|
|
<h3><a class="mozTocH3" name="mozTocId802428"></a> 7.5.4 <span
|
|
style="font-weight: bold;">Skip likely duplicates</span></h3>
|
|
All of the above may be used together with the regular database
|
|
facility of XEphem. If this option is on, XEphem eliminates what
|
|
appears to be redundant entries for the same star from the various
|
|
catalogs. Two stars are considered the same if their positions match
|
|
within the given number of arcseconds and their brightnesses differ by
|
|
less than the given number of magnitudes. (The generous default
|
|
magnitude tolerance is because the GSC and the PPM use varying
|
|
filters).<br>
|
|
<br>
|
|
When deciding on the final selection for such duplicate entries the
|
|
highest priority is the local database, then the HD or SAO entry,
|
|
then the PPM entry, then Hipparcos, then Tycho and finally the GSC
|
|
entry.When you have made the desired entries, pressing <span
|
|
style="font-weight: bold;">Apply</span> will attempt to check each
|
|
filename, directory and Internet choice, as appropriate. The cursor
|
|
will be a Watch while the tests are in progress. If something does not
|
|
seem correct, a warning window will appear and the option will be
|
|
turned back off. If everything seems to be operating correctly, you
|
|
are in business. The <span style="font-weight: bold;">Ok</span> button
|
|
does the same thing but then also closes the window if they all
|
|
succeed.<br>
|
|
<br>
|
|
<h3><a class="mozTocH3" name="mozTocId289990"></a> 7.5.5 Notes</h3>
|
|
If at any time something goes wrong during the acquisition of any
|
|
Field Stars from any View, the responsible option in that view is also
|
|
turned off automatically. The problem should be corrected and Field
|
|
stars turned on again.<br>
|
|
<br>
|
|
All field star sources will silently enforce limits on the total number
|
|
of stars they yield for any query. As of this writing, local queries
|
|
except USNO are limited to 30 degrees; USNO are limited to 15 degrees;
|
|
network queries impose various limits.<br>
|
|
<br>
|
|
<h1><a class="mozTocH1" name="mozTocId915560"></a> 8.0 <span
|
|
style="font-weight: bold;">Preferences<br>
|
|
</span></h1>
|
|
The simple choice preferences are covered in the Main Window section.
|
|
See <a href="#MainMenu_preferences">Preferences menu</a>,<br>
|
|
<h2><a class="mozTocH2" name="mozTocId361550"></a> 8.1 <a name="Save_fonts"></a>
|
|
Fonts</h2>
|
|
<div style="text-align: left;"> <img
|
|
style="width: 450px; height: 600px;" alt="" title=""
|
|
src="png/save-fonts.png" align="right" hspace="20">This
|
|
window lets you change most of the fonts used by XEphem. The basic
|
|
technique is to specify a font, use the four toggle buttons to choose
|
|
which action to take then perform the action in a particular font
|
|
context by clicking in the menus accessed from the menubar across the
|
|
top. </div>
|
|
<br>
|
|
To browse the available fonts, type a pattern in the field provided and
|
|
click <span style="font-weight: bold;">Search</span>. This will
|
|
display
|
|
the names of all fonts matching a pattern. To see all available fonts,
|
|
use the wild card pattern of a single star (*). To be more specific,
|
|
specify the fields desired and fill the gaps between with the star
|
|
wildcard. See the next section for a description of each field.<br>
|
|
<br>
|
|
Clicking a font in the top list will display a sample and its full name
|
|
in the region at the bottom.<br>
|
|
<br>
|
|
The <span style="font-weight: bold;">Buttons,</span> <span
|
|
style="font-weight: bold;">Text</span> and <span
|
|
style="font-weight: bold;">Other</span> menus in the menu bar across
|
|
the top provide ways of referring to several font contexts. The four
|
|
toggle buttons just below the menu bar determines what happens when one
|
|
of these context menu buttons is clicked, as follows:<br>
|
|
<br>
|
|
<span style="font-weight: bold;">Get current</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> When this toggle is active, clicking a
|
|
context menu button will cause the name of the current font for that
|
|
context to be displayed in the pattern field and history list. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Get default</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> When this toggle is active, clicking a
|
|
context menu button will cause the name of the last saved default
|
|
font for that context to be displayed in the pattern field and
|
|
history list. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Set</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> When this toggle is active, clicking a
|
|
context menu button will cause the font named in the pattern field
|
|
of this window to be applied to that context throughout XEphem. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Restore default</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> When this toggle is active, clicking a
|
|
context menu button will cause its last saved font value to be
|
|
reinstated through XEphem. </div>
|
|
<br>
|
|
Fonts that have been changed from their default values are tagged in
|
|
the <span style="font-family: monospace;">Preferences » Save</span>
|
|
window (when opened or after you do a Refresh). This allows you to Save
|
|
the new fonts set here permanently. If you do not Save it, the change
|
|
only effects XEphem until you exit.<br>
|
|
<br>
|
|
There are a few situations scattered around within XEphem for which
|
|
changing fonts at runtime from this window does not work perfectly.
|
|
For example, changing to a smaller font does not shrink some windows
|
|
as much as you might expect. Such anomalies are known challenges and
|
|
do not indicate serious problems. After Saving the fonts and
|
|
restarting XEphem, all will work again as expected.<br>
|
|
<h3><a class="mozTocH3" name="mozTocId523543"></a> 8.1.1 XLFD</h3>
|
|
The font names are in the format called X Logical Font Description.
|
|
There are 15 fields separated by hyphens. The fields are as follows:<br>
|
|
<br>
|
|
<div style="margin-left: 40px;">
|
|
<dl>
|
|
<dt>Foundry<br>
|
|
</dt>
|
|
<dd><br>
|
|
The organization that digitized the font data.</dd>
|
|
</dl>
|
|
Family<br>
|
|
<dl>
|
|
<dd>The commercial name of the font.</dd>
|
|
</dl>
|
|
Weight<br>
|
|
<dl>
|
|
<dd>The relative weight of the font, such as bold, medium or regular.<br>
|
|
</dd>
|
|
</dl>
|
|
Slant<br>
|
|
<dl>
|
|
<dd>A code indicating the slant:</dd>
|
|
</dl>
|
|
<div style="margin-left: 80px;"> r Roman (no slant)<br>
|
|
i Italic (slant left)<br>
|
|
o Oblique (slant left) <br>
|
|
</div>
|
|
Set Width<br>
|
|
<dl>
|
|
<dd>The width with respect to what the foundry considered normal.
|
|
Choices include normal, condensed, narrow, double.</dd>
|
|
</dl>
|
|
Additional Style<br>
|
|
<dl>
|
|
<dd>Anything else needed to uniquely identify the font, such as sans
|
|
or serif.<br>
|
|
</dd>
|
|
</dl>
|
|
Pixel Size<br>
|
|
<dl>
|
|
<dd>The height of an <span style="font-style: italic;">em</span> in
|
|
pixels.</dd>
|
|
</dl>
|
|
Point Size<br>
|
|
<dl>
|
|
<dd>The height of an <span style="font-style: italic;">em</span> in
|
|
tenths of a point, where one point is 1/72 inch.</dd>
|
|
</dl>
|
|
Horizontal Resolution<br>
|
|
Vertical Resolutoin<br>
|
|
<dl>
|
|
<dd>The resolution of the device for which the font was designed, in
|
|
pixels-per-inch.</dd>
|
|
</dl>
|
|
Spacing<br>
|
|
<dl>
|
|
<dd>A code indicating the spacing between characters in the font:</dd>
|
|
</dl>
|
|
<div style="margin-left: 80px;"> M Monospaced (fixed pitch)<br>
|
|
P Proportional spaced (variable pitch)<br>
|
|
C Character cell (each character occupies the same size box) <br>
|
|
<br>
|
|
</div>
|
|
Average Width<br>
|
|
<dl>
|
|
<dd>Average width of all characters in the font, measured in tenths
|
|
of
|
|
a pixel.</dd>
|
|
</dl>
|
|
Registry<br>
|
|
Enoding<br>
|
|
<dl>
|
|
<dd>The registration authority and their name for the character set
|
|
from which the characters in the font are drawn. For example ISO8859-1,
|
|
also known as Latin-1.</dd>
|
|
</dl>
|
|
</div>
|
|
Scalable fonts are indicated by 0 for point size, pixel size, x and y
|
|
resolution and average width (fields 7, 8, 9, 10 and 12). To choose a
|
|
specific scalable font, specify desired values for some but not all of
|
|
these fields, letting the system fill in the others.<br>
|
|
<br clear="all">
|
|
<h2><a class="mozTocH4" name="mozTocId759084"></a> 8.2 <a name="Save_colors"></a>
|
|
Colors</h2>
|
|
<img style="width: 300px; height: 310px;" alt="" title=""
|
|
src="png/save-colors.png" align="right" height="310" hspace="20"
|
|
width="300">This window lets you change most of the
|
|
colors used by XEphem. The basic technique is to use the four toggle
|
|
buttons to choose which action to take then perform the action in a
|
|
particular color context by clicking in the menus accessed from the
|
|
menubar across the top.<br>
|
|
<br>
|
|
The possible actions are as follows:<br>
|
|
<br>
|
|
<span style="font-weight: bold;">Get current</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> When this toggle is active, clicking a
|
|
color context menu button will cause the current color for that
|
|
context to be displayed in the color patch in the lower right corner
|
|
of this window. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Get default</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> When this toggle is active, clicking a
|
|
color context menu button will cause the last saved default color
|
|
for that context to be displayed in the color patch in the lower
|
|
right corner of this window. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Set</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> When this toggle is active, clicking a
|
|
color context menu button will cause the color currently being
|
|
displayed in the color patch of this window to be applied to that
|
|
context throughout in XEphem. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Restore default</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> When this toggle is active, clicking a
|
|
color context menu button will cause its last saved color to be
|
|
reinstated. </div>
|
|
<br>
|
|
Above the color patch are three sliding scales that allow you to define
|
|
a color using either Red+Green+Blue or Hue+Saturation+Value, depending
|
|
on the toggle. Each scale ranges from 0 through 255. Hue is the basic
|
|
spectral color, where 0 is red, 85 is green, 170 is blue. Saturation
|
|
is the amount of color purity, where lower values mix in more white.
|
|
Value is like brightness, where 0 is totally black.<br>
|
|
<br>
|
|
The text field at lower left allows you to type a color using one of
|
|
the standard descriptive names, such as "steel blue", or in hex RGB
|
|
notation, for example #ff0000 for pure red, #00ff00 for pure green
|
|
#0000ff for pure blue. After typing the desired value, press Enter to
|
|
set the scales and see the color in the patch. This field is also set
|
|
automatically when the scales are used to set a color, during Grabbing
|
|
(see next), and when a color context is retrieved.<br>
|
|
<br>
|
|
The history list in the lower left stores each color name that is used
|
|
from the name field, making it easier to reuse a color. Selecting a
|
|
name
|
|
will copy it to the name field and show it in the color patch. You can
|
|
select history entries with the mouse, or by browsing with the Up and
|
|
Down keyboard arrow keys.<br>
|
|
<br>
|
|
<h3><a class="mozTocH3" name="mozTocId896872"></a> 8.2.1 <span
|
|
style="font-weight: bold;">Colors Control menu</span></h3>
|
|
<br>
|
|
<div style="margin-left: 40px;"><span style="font-weight: bold;">Night
|
|
mode</span><br>
|
|
<span style="font-weight: bold;"></span></div>
|
|
<span style="font-weight: bold;"><br>
|
|
</span>
|
|
<div style="margin-left: 80px;">This changes the XEphem background to
|
|
black, and uses the Night vision color for all text. Clicking this
|
|
back off will restore the previous colors. Note that when Night vision
|
|
is on, you may not change the colors it effects. This is to eliminate
|
|
confusion with regards to whether or not they are new in the Save
|
|
window.<br>
|
|
</div>
|
|
<br>
|
|
<div style="margin-left: 40px;"><span style="font-weight: bold;">Grab
|
|
color</span><br>
|
|
<span style="font-weight: bold;"></span></div>
|
|
<span style="font-weight: bold;"><br>
|
|
</span>
|
|
<div style="margin-left: 80px;">Press this button and the cursor will
|
|
change to a crosshair. Move the cursor around on the screen and the
|
|
color of the pixel under the crosshair will be displayed; press
|
|
Button1 to capture the color and resume normal cursor operation.<br>
|
|
</div>
|
|
<br>
|
|
<div style="margin-left: 40px;"><span style="font-weight: bold;">Clear
|
|
history</span> <br>
|
|
</div>
|
|
<br>
|
|
<div style="margin-left: 80px;">Erases all entries in the History list.<br>
|
|
</div>
|
|
<br>
|
|
<br>
|
|
When a color context is changed, it also changes the corresponding
|
|
resource. In the <span style="font-family: monospace;">Preferences
|
|
» Save</span> window you will notice that the resource becomes
|
|
marked as Modified (when opened or after you do a Refresh). This
|
|
allows you to Save the new color choice permanently. If you do not
|
|
Save it, the change only effects XEphem until you exit.<br>
|
|
<br>
|
|
<h3><a class="mozTocH3" name="mozTocId803196"></a> 8.2.2 Star colors</h3>
|
|
XEphem assigns colors to stars based on their spectral classification.
|
|
The default colors were chosen based on work done by <a
|
|
href="http://www.vendian.org/mncharity/dir3/starcolor">Mitchell Charity</a>.
|
|
The colors are specified using X Resources. The resource names each
|
|
begin with "XEphem.starSpect" followed by one or two characters. The
|
|
value of the resource is the color. The following table shows the
|
|
default spectral color resources built into XEphem:<br>
|
|
<br>
|
|
<br>
|
|
<table
|
|
style="text-align: left; margin-left: auto; margin-right: auto; width: 60%;"
|
|
border="0" cellpadding="2" cellspacing="2">
|
|
<tbody>
|
|
<tr>
|
|
<th style="vertical-align: top;">XEphem Resource Name<br>
|
|
</th>
|
|
<th style="vertical-align: top;">Default Color Value<br>
|
|
</th>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-family: monospace;">XEphem.starSpectO</td>
|
|
<td style="vertical-align: top; font-family: monospace;">#9bb0ff</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-family: monospace;">XEphem.starSpectB</td>
|
|
<td style="vertical-align: top; font-family: monospace;">#aabfff</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-family: monospace;">XEphem.starSpectA</td>
|
|
<td style="vertical-align: top; font-family: monospace;">#cad7ff</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-family: monospace;">XEphem.starSpectF</td>
|
|
<td style="vertical-align: top; font-family: monospace;">#f8f7ff</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-family: monospace;">XEphem.starSpectG</td>
|
|
<td style="vertical-align: top; font-family: monospace;">#fff4ea</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-family: monospace;">XEphem.starSpectK</td>
|
|
<td style="vertical-align: top; font-family: monospace;">#ffd2a1</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-family: monospace;">XEphem.starSpectM</td>
|
|
<td style="vertical-align: top; font-family: monospace;">#ffcc6f</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-family: monospace;">XEphem.starSpectN</td>
|
|
<td style="vertical-align: top; font-family: monospace;">#ff8f2c</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-family: monospace;">XEphem.starSpectS</td>
|
|
<td style="vertical-align: top; font-family: monospace;">#ffc574</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-family: monospace;">XEphem.starSpectC</td>
|
|
<td style="vertical-align: top; font-family: monospace;">#ff9e40</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-family: monospace;">XEphem.starSpectT</td>
|
|
<td style="vertical-align: top; font-family: monospace;">#ffd19a</td>
|
|
</tr>
|
|
<tr>
|
|
<td style="vertical-align: top; font-family: monospace;">XEphem.starSpectW</td>
|
|
<td style="vertical-align: top; font-family: monospace;">#c4c4ff</td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
<br>
|
|
<br>
|
|
XEphem uses the closest entry with matching first character. If no
|
|
entry is found with matching first character then white is used and a
|
|
message is added to the <a href="#SysLog">System log</a>. The
|
|
spectral color resource values may be edited or additional resources
|
|
can
|
|
be added but this must be done by hand, there is no GUI support
|
|
available. Always edit the XEphem resource file while XEphem is <span
|
|
style="font-style: italic;">not running</span> to avoid any chance of
|
|
conflict.<br>
|
|
<h2><a class="mozTocH2" name="mozTocId376242"></a> 8.3 <a name="Save"></a>Save</h2>
|
|
<img alt="" src="png/save-resources.png" align="right" height="290"
|
|
hspace="10" vspace="5" width="394">This window displays all of the
|
|
options,
|
|
settings and controls, collectively called Preferences, throughout
|
|
XEphem that may be saved and
|
|
reinstated next time the program is started. XEphem has many such
|
|
preferences, so
|
|
they are separated into categories in this window for easier
|
|
management. Each category may be expanded or collapsed using the
|
|
+/- toggle square to show each individual preference.<br>
|
|
<br>
|
|
Preferences are saved using the standard Resource mechanism provided by
|
|
the X Window System. These resources are saved in the file <b>XEphem</b>
|
|
located in the <a href="#SharedPrivateDirs">Private</a> directory.<br>
|
|
<br>
|
|
Each preference may be tagged for saving. The toggle at the top
|
|
controls whether all tagged preferences will be <b>Autoatically save</b>d
|
|
when XEphem is Quit.<br>
|
|
<br>
|
|
Preferences have been divided into two classes.<br>
|
|
<blockquote><b>Major</b>: In the opinion of the author these
|
|
preferences are sufficiently interesting that they are likely to be
|
|
worth saving and automatically restoring between one invocation of
|
|
XEphem and the next.<br>
|
|
<br>
|
|
<b>Minor</b>: Everything else, presumably less critical in nature. It
|
|
is expected that you are likely to
|
|
change these preferences frequently in due course while operating
|
|
XEphem yet they do not cause major effects on program behavior so
|
|
saving them at
|
|
any one particular setting is not especially compelling. Minor
|
|
preferences are things like window size and position, scale settings
|
|
which
|
|
only effect views, and all of the Sky View Filter and Option settings.<br>
|
|
<br>
|
|
This distinction is of course rather arbitrary so please take
|
|
care when changing and saving preferences so the ones you want are
|
|
saved.<br>
|
|
</blockquote>
|
|
<blockquote>The number of preferences in each class currently tagged
|
|
for saving is indicated by messages near the top.<br>
|
|
</blockquote>
|
|
The scrolled area can display each preference, whether it is tagged for
|
|
saving and the ability to change whether it is tagged. Each category of
|
|
preference can be expanded for more detail using the +/- toggle square.<br>
|
|
<blockquote>In the expanded view, each preference and its value are
|
|
shown exactly
|
|
as it will appear in the disk file if Saved. Those preferences
|
|
which differ from the last time they were Saved, or since XEphem was
|
|
started if no Save has yet occurred, are marked with a bullet. Major
|
|
preferences are marked with a solid bullet, Minor preferences with an
|
|
hollow
|
|
bullet. A toggle next to each preference allows individual selection
|
|
over whether the preference will be written to disk on the next Save.
|
|
After each Refresh, the toggles are set for those preferences found to
|
|
have changed since the last Save if their class is set to be
|
|
automatically tagged. Each toggle may be changed manually in either
|
|
direction to override this automatic behavior on an individual basis
|
|
if desired but not these will be overridden with the next Refresh.<br>
|
|
<br>
|
|
In the collapsed view, if at least one Major preference is out of date
|
|
in a category, a solid bullet is placed next to the category heading;
|
|
otherwise if at least one Minor preference is out of date a hollow
|
|
bullet is used.<br>
|
|
</blockquote>
|
|
<blockquote>
|
|
Note that the information in this window does <em>not</em>
|
|
automatically track changes in preferences as XEphem is used. You must
|
|
use Refresh to update the status manually when desired. In particular,
|
|
the values which are Saved are what they were the last time Refresh
|
|
was performed, not what they actually are at the moment Save is
|
|
activated.<br>
|
|
</blockquote>
|
|
<br>
|
|
<span style="font-weight: bold;">Save now</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;">Write each tagged preference to disk to
|
|
the XEphem resource file.
|
|
If the file already exists, it will first be copied to XEphem.bak in
|
|
the same directory. If a preference already exists in the file it will
|
|
be
|
|
edited in-place, otherwise a new entry is added at the bottom. Other
|
|
lines in the file are left unchanged. After using Save, all preferences
|
|
will be considered up to date, even if they were not selected to be
|
|
written to the preference file. </div>
|
|
<br>
|
|
<div style="margin-left: 40px;"> N.B. The values saved are as they
|
|
appear in this window, which may be different from their current
|
|
value if they have changed since the last Refresh. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Refresh</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> Update the changed and save status of
|
|
each preference. This refresh action also
|
|
happens automatically <i>after</i> a Save is performed and just before
|
|
XEphem quits when deciding which preferences to save if the Automatic
|
|
saving option is enabled. </div>
|
|
<h1><a class="mozTocH1" name="mozTocId539636"></a> 9.0 <span
|
|
style="font-weight: bold;">Multifunction Tools</span></h1>
|
|
The tools in this section are used in several different places
|
|
throughout XEphem. The descriptions here are generic. If there are any
|
|
special issues when used in certain contexts they will be described in
|
|
the appropriate sections elsewhere.<br>
|
|
<div style="margin-left: 40px;"></div>
|
|
<a name="Trails"></a>
|
|
<h2><a class="mozTocH1" name="mozTocId242681"></a> 9.1 Trails</h2>
|
|
<img alt="" src="png/trails.png" align="right" height="416" hspace="20"
|
|
width="400"> This
|
|
window allows you to define a set of time values spaced at regular
|
|
intervals before and after the current XEphem time and define which
|
|
and in what manner values will be annotated with a time stamp.<br>
|
|
<br>
|
|
This is a general purpose facility used in several places throughout
|
|
XEphem, generally for the purpose of establishing a trail of object
|
|
motion. This description will be of a general nature.<br>
|
|
<br>
|
|
Six format parameters must be specified:<br>
|
|
<br>
|
|
<span style="font-weight: bold;">Orientation<br>
|
|
<br>
|
|
</span>
|
|
<div style="margin-left: 40px;"> This choice determines where the
|
|
stamps
|
|
appear in relation to their corresponding position mark. The first
|
|
several options should be self-explanatory. The last two, Path-left and
|
|
Path-right, cause the time stamps
|
|
to be placed to the left or right side of the trail path, as one would
|
|
perceive these directions when traversed in forward time order. In
|
|
no case are the time stamps ever drawn to require you to turn your
|
|
head more than 90 degrees left or right. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Interval</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This is the time interval between each
|
|
step. Choose from among several predefined intervals or choose Custom
|
|
and enter any desired interval
|
|
in the space provided. It is okay to specify more than 24 hours to
|
|
achieve intervals of several days. It is also okay to specify negative
|
|
values to run time backwards. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Label</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This choice determines which intervals
|
|
will to be labeled with a time stamp. Choose from among several
|
|
options or choose None if no labeling
|
|
is desired. Times will be printed surrounded by parentheses if the
|
|
object is an Earth satellite and it is eclipsed.</div>
|
|
<br>
|
|
<span style="font-weight: bold;">Format</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This choice determines the format in
|
|
which to display
|
|
each time-stamp. Choose Hour:Minute
|
|
with or without Seconds or the date formatted as per the <span
|
|
style="font-family: monospace;">Preferences » Date formats</span>
|
|
option in the Main menubar, see <a href="#MainMenu_preferences">Preferences</a>.</div>
|
|
<br>
|
|
<span style="font-weight: bold;">Font</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This choice sets the size of the
|
|
annotation text font. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Start</span><br>
|
|
<br>
|
|
<div style="margin-left: 40px;"> This choice specifies how the first
|
|
time value is derived from the current XEphem time. The lower right
|
|
radio box offers several methods of determining the beginning of the
|
|
first time interval. The idea here is generally to match the time
|
|
values of each time mark with the precision implied by the format, but
|
|
to allow other options for special situations.<br>
|
|
<br>
|
|
<span style="font-weight: bold;">Whole min</span> rounds the current
|
|
XEphem time forward to the next whole minute, if necessary;<br>
|
|
<span style="font-weight: bold;">Whole day</span> rounds to the next
|
|
whole day.<br>
|
|
<span style="font-weight: bold;">Whole interval</span> rounds to the
|
|
next whole multiple of whatever time interval is set (as specified
|
|
in the Intervals choices).<br>
|
|
<span style="font-weight: bold;">Now</span> means to begin with the
|
|
current XEphem time without any initial changes. </div>
|
|
<br>
|
|
Two scales near the bottom specify the number of tick marks to create
|
|
before and after the starting time.<br>
|
|
<br>
|
|
Once the choices are set up as desired, <span
|
|
style="font-weight: bold;">Ok</span> will create the trail and the
|
|
window will disappear. <span style="font-weight: bold;">Apply</span>
|
|
will create the trail but the window will remain up for further use. <span
|
|
style="font-weight: bold;">Close</span> just dismisses the window
|
|
without creating a trail.<br>
|
|
<br>
|
|
Even with all this flexibility pleasingly annotated trails are not
|
|
trivial to generate. It is hoped that a little experimentation can
|
|
yield acceptable results in most cases. Note that this general trail
|
|
facility does not provide close coupling with the view being
|
|
supported. For example, some views do not support setting a trail for
|
|
an object which has changed while the Trail Setup is up. Also, views
|
|
may vary in their support of having trails defined while they are not
|
|
visible. Each view may establish its own initial default values but
|
|
changes usually remain in effect for subsequent instances of Trail
|
|
Setup windows from the same view. Some views permit more than one
|
|
Trail Setup to be active at one time. In short, the operational
|
|
boundary conditions vary by view. <br>
|
|
<br>
|
|
The settings for each view context may be saved using
|
|
<span style="font-family: monospace;">Preferences » Save</span>.
|
|
<a name="Print"></a>
|
|
<h2><a class="mozTocH1" name="mozTocId231234"></a> 9.2 Printing</h2>
|
|
<img alt="" src="png/print.png" align="right" height="182" width="249">This
|
|
window lets you print the current view or save it to a file. In either
|
|
case the format used is Postscript.<br>
|
|
<br>
|
|
<span style="font-weight: bold;">Title<br>
|
|
<br>
|
|
</span>
|
|
<div style="margin-left: 40px;"> If you enter a string in the text
|
|
field
|
|
labeled Title, the string will be printed centered across the top of
|
|
the page. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Color<br>
|
|
Black<br>
|
|
<br>
|
|
</span>
|
|
<div style="margin-left: 40px;"> The top left pair of toggle buttons
|
|
allow you to choose whether color commands will be included in the
|
|
Postscript generated. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Letter<br>
|
|
A4<br>
|
|
<br>
|
|
</span>
|
|
<div style="margin-left: 40px;"> The center pair offer the choice of US
|
|
Letter size 8½x11" with ¾" margin or ISO A4 210x297mm
|
|
with 15mm margin. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Thin lines<br>
|
|
Thick lines<br>
|
|
<br>
|
|
</span>
|
|
<div style="margin-left: 40px;"> The right pair offer the choice of
|
|
drawing with very thin lines or somewhat thicker lines. </div>
|
|
<br>
|
|
<span style="font-weight: bold;">Save to file<br>
|
|
<br>
|
|
</span>
|
|
<div style="margin-left: 40px;"> If you choose to Save to a file, turn
|
|
on that toggle button and enter the desired file name in the text
|
|
box to the right of the toggle button. Unless begun with a / the
|
|
file name is in the <a href="#SharedPrivateDirs">Private</a> directory.<br>
|
|
</div>
|
|
<br>
|
|
<span style="font-weight: bold;">Print command<br>
|
|
<br>
|
|
</span>
|
|
<div style="margin-left: 40px;"> If you choose to print directly to the
|
|
printer, turn on that toggle button and enter a command which will
|
|
print a Postscript file on your system. The command should expect
|
|
the name of a file to print as its first and only argument. A
|
|
temporary file will automatically be created for this command and
|
|
deleted when printing is completed. You can also enter a command
|
|
here that will display the file, such as gv to preview the file then
|
|
and print from there. </div>
|
|
<br>
|
|
When ready, click <span style="font-weight: bold;">Ok.</span> To avoid
|
|
printing, press <span style="font-weight: bold;">Cancel.</span> If
|
|
your
|
|
current viewing fonts are not available for printing, error recovery
|
|
will depend upon your local print system. <a name="Annotation"></a>
|
|
<h2><a class="mozTocH1" name="mozTocId406792"></a> 9.3 Annotation</h2>
|
|
<div style="margin-left: 40px;">
|
|
<div align="left"> </div>
|
|
</div>
|
|
<img alt="" src="png/annotation.png" align="right" height="156"
|
|
hspace="10" width="350">This window allows you to add your own text
|
|
and lines to any graphical
|
|
view. Annotation locations are saved in the world coordinates of the
|
|
view. For example, in the Earth view they are saved in Lat and Long. In
|
|
the Sky View, they are saved in the current display mode, that is,
|
|
either RA/Dec or Alt/Az. The window shows which view each annotation
|
|
refers to.<br>
|
|
<br>
|
|
You may <b>Save</b> the current set of annotations to the specified
|
|
file or <b>Load</b> a set by selecting from the files presented in the
|
|
pop-down menu. Annotation files use the suffix .ano. XEphem tries to
|
|
automatically load the file specified in the Save field when it starts.
|
|
This
|
|
file name can be saved in the <tt>Preferences <span
|
|
style="font-family: monospace;">»</span> Save </tt>window in
|
|
the Annotation section.<br>
|
|
<br>
|
|
To add a new annotation entry:<br>
|
|
<br>
|
|
<ol>
|
|
<li>click <b>New</b> to create a blank entry,</li>
|
|
<li>type in the desired text,</li>
|
|
<li>click <b>Place</b> to begin the placement procedure,</li>
|
|
<li>move the cursor to position the text where desired,</li>
|
|
<li>click and hold to anchor the text and begin drawing a line,</li>
|
|
<li>move the pencil cursor to position the far end of the line as
|
|
desired,</li>
|
|
<li>release.</li>
|
|
</ol>
|
|
<br>
|
|
To move an existing entry, click <b>Place</b>
|
|
again and proceed as above with step 4.<br>
|
|
<br>
|
|
To draw just a line with no text, leave the text field blank.<br>
|
|
<br>
|
|
To place text with no line, immediately release after anchoring the
|
|
text.<br>
|
|
<br>
|
|
To change just the text of an existing entry, edit the text and type
|
|
Enter.<br>
|
|
<br>
|
|
To temporarily hide one entry, click <b>Hide</b> on its line. To hide
|
|
all entries click <b>Hide all</b>, to toggle which entries are hidden
|
|
click <b>Toggle</b>.<br>
|
|
<br>
|
|
To delete an entry, click <b>Delete.</b> <br>
|
|
<br>
|
|
<h1><a class="mozTocH1" name="mozTocId429783"></a> 10.0 <a name="Credits"></a>Credits</h1>
|
|
The following are in no particular order but all are greatly
|
|
appreciated:
|
|
<p>Thanks to Lutz Mandle for restoring SOHO support in 2012; showing sun in
|
|
moonview; proxy support in web downloads; improved horizon clipping and
|
|
correct use of Sky View options in individual planetary views.
|
|
<p>Enormous advances in data quality were
|
|
contributed by the late Guillermo Andrade Velasco. <p>
|
|
<p>The Blue Marble project at
|
|
<a target="new"
|
|
href="http://earthobservatory.nasa.gov/Newsroom/BlueMarble">http://earthobservatory.nasa.gov/Newsroom/BlueMarble
|
|
</a>for their
|
|
wonderful
|
|
whole-earth color images.</p>
|
|
<p>
|
|
Corrections for ecliptic longitude from Adrian Robinson, adrianprobinson@yahoo.co.uk </p>
|
|
<p>The stellar spectra colors are based on work by Mitchell Charity,
|
|
mcharity@lcs.mit.edu, at
|
|
<a target="new" href="http://www.vendian.org/mncharity/dir3/starcolor">http://www.vendian.org/mncharity/dir3/starcolor.
|
|
</a> </p>
|
|
<p>Thanks to Paul Schlyter for some improved anomaly code.<br>
|
|
</p>
|
|
<p>Dean Huxley contributed improved constellation figures and improved
|
|
the Tycho Hipparcos data base.<br>
|
|
</p>
|
|
<p>
|
|
Thanks to Thomas Conze, thomas.conze@gmx.net, for several great
|
|
patches.
|
|
</p>
|
|
<p>Thanks to Matei Conovici, cmatei@profis.ro, for making Sky View's "live
|
|
report" option a saveable preference.</p>
|
|
<p>Several nice tweaks and some thorough debugging from John O'Donnell,
|
|
jmodonnell@earthlink.net.
|
|
</p>
|
|
<p>
|
|
Thanks to Jean-loup Gailly and Mark Adler for zlib.
|
|
</p>
|
|
<p>
|
|
Thanks to Eric S. Raymond for his fine implementation of base64.
|
|
</p>
|
|
<p>Milky Way contour by Pertti Paakkonen, ppaakko@cc.joensuu.fi, in
|
|
turn
|
|
based on map from http://www.ebicom.net/~rsf1/fun/sm-new.htm copyright
|
|
(c)
|
|
1972,2001, R.S. Fritzius, may be reproduced for non-commercial purpose.
|
|
</p>
|
|
<p>The local magnetic declination model is from the DoD World Magnetic
|
|
Model as published at <a target="new"
|
|
href="http://www.ngdc.noaa.gov/seg/potfld/DoDWMM.shtml">http://www.ngdc.noaa.gov/seg/potfld/DoDWMM.shtml
|
|
</a> </p>
|
|
<p>Thanks to Fridger Schrempp, fridger.schrempp@desy.de, for his long
|
|
term encouragement of the project, and particularly for many
|
|
suggestions
|
|
to improve ease of use.</p>
|
|
<p>Thanks to Wolfgang Steinicke of www.ngcic.org for allowing use of
|
|
his corrected NGC and IC catalogs.</p>
|
|
<p>Earth satellite orbit propagation is based on the NORAD SGP4/SDP4
|
|
code, as converted from FORTRAN to C by Magnus Backstrom,
|
|
b@eta.chalmers.se. See "Spacetrack Report Number 3: Models for
|
|
Propagation of NORAD Element Sets" at
|
|
<a target="new"
|
|
href="http://www.celestrak.com/NORAD/documentation/spacetrk.pdf">http://www.celestrak.com/NORAD/documentation/spacetrk.pdf</a>
|
|
</p>
|
|
<p>Improvements to Delta T code, help and wording contributed by Neal
|
|
McBurnett, nealmcb@bell-labs.com.</p>
|
|
<p>Any parts of the USNO SA2.0 catalog that are included with XEphem
|
|
distributions are done so with the following understandings:</p>
|
|
<blockquote> It may not be the latest version, check with <a
|
|
target="new" href="http://ad.usno.navy.mil">http://ad.usno.navy.mil</a>
|
|
<p>If you paid for XEphem, you paid for the software, not this
|
|
catalog. The catalog is available free from the USNO.</p>
|
|
<p>Inclusion of the SA2.0 catalog does not imply an endorsement of
|
|
XEphem by USNO; nor did I have privileged access to the catalog; nor
|
|
does the US Government affirm or guarantee that XEphem works
|
|
properly in any way.</p>
|
|
</blockquote>
|
|
Thanks to Atsuo Ohki, ohki@gssm.otsuka.tsukuba.ac.jp, for numerous
|
|
fixes and features.
|
|
<p>Thanks to Robert Lane, roblane@alum.mit.edu, for Uranonmetria 2000
|
|
work.</p>
|
|
<p>
|
|
Martian relief map completed June 2000 using data from Mars Orbiter
|
|
Laser
|
|
Altimeter on board the Mars Global Surveyor, operated by the Jet
|
|
Propulsion
|
|
Laboratory, NASA.
|
|
See <a target="new" href="http://marsprogram.jpl.nasa.gov/mgs">http://marsprogram.jpl.nasa.gov/mgs</a>
|
|
</p>
|
|
<p>The near real-time weather map in the Earth view is provided by
|
|
the Space Science and Engineering Center at the University of
|
|
Wisconsin.
|
|
See their web site at <a target="new"
|
|
href="http://www.ssec.wisc.edu/ssec.html">http://www.ssec.wisc.edu/ssec.html</a>
|
|
</p>
|
|
<p>The XEphem logo was contributed by Jonathan Adams,
|
|
jfadams@mail.arc.nasa.gov. The galaxy background image is from Galaxy
|
|
Photography, www.galaxyphoto.com.</p>
|
|
<p>For the years 1999-2010 the natural satellite ephemerides for Mars,
|
|
Jupiter, Saturn and Uranus are based on developments in mixed
|
|
functions computed and contributed at Bureau Des Longitudes,
|
|
<a target="new" href="http://www.bdl.fr">http://www.bdl.fr</a>
|
|
by J.-E. Arlot, Ch. Ruatti and W. Thuillot. Many
|
|
thanks!</p>
|
|
<p>Outside this range, Jupiter's moons based on information in
|
|
"Astronomical Formulae for Calculators" by Jean Meeus. Richmond, Va.,
|
|
U.S.A., Willmann-Bell, (c) 1982. Saturn's moons based on code and
|
|
ideas supplied by Dan Bruton, Texas A&M, astro@sfasu.edu. For all
|
|
dates, ring tilts based on "RINGS OF SATURN" program by Olson, et al,
|
|
Sky & Telescope, May 1995, page 95. C code as converted from BASIC
|
|
by pmartz@dsd.es.com (Paul Martz).</p>
|
|
<p>Thanks to Monty Brandenberg, mcbinc@world.std.com, for his
|
|
assistance and solution to the unaligned access messages on Digital
|
|
UNIX.</p>
|
|
<p>Thanks to Christophe Magneville, cmv@hep.saclay.cea.fr, for finding
|
|
an array subscript and a numeric overflow problem in libastro.</p>
|
|
<p>Thanks to Jean-Etienne Lamiaud for a fix to
|
|
prevent gif color tables from hogging more than their share of X
|
|
colormap entries, many corrections to xephem_sites, and a nice speedup
|
|
to
|
|
Sky View depth sorting.</p>
|
|
<p>Thanks to Egil Kvaleberg, egil@kvaleberg.no, for key idea on how to
|
|
support 8 bit FITS images.</p>
|
|
<p>Thanks to Stuart Levy, slevy@ncsa.uiuc.edu, for his work converting
|
|
the Tycho ESA mission database
|
|
adc.gsfc.nasa.gov:/pub/adc/archives/catalogs/1/1239 into xe format.</p>
|
|
<p>Images of Saturn from STScI.</p>
|
|
<p>Many formulas and tables are based, with permission, on material
|
|
found in: "Astronomy with your Personal Computer" by Dr. Peter
|
|
Duffett-Smith, Cambridge University Press, (c) 1985.</p>
|
|
<p>The high precision planet positions were implemented for XEphem by
|
|
Michael Sternberg <sternberg@physik.tu-chemnitz.de> based on the
|
|
papers</p>
|
|
<ol>
|
|
<li>"Planetary Theories in rectangular and spherical variables:
|
|
VSOP87 solution" by Bretagnon P., Francou G., in Astron. Astrophys.
|
|
202, 309 (1988), ftp://ftp.bdl.fr/pub/ephem/planets/vsop87/, and</li>
|
|
<li>"Representation of planetary ephemerides by frequency analysis.
|
|
Application to the five outer planets" by Chapront J., Astron.
|
|
Astrophys. Suppl. Ser. 109, 181 (1995), ftp://adc.gsfc.nasa.gov/\
|
|
pub/adc/archives/journal_tables/A+AS/109/181.</li>
|
|
</ol>
|
|
See the comments in chap25.h and vsop87.h for accuracy estimates.
|
|
<p>The high precision Moon code was also implemented for XEphem by
|
|
Mr. Sternberg based on code supplied by Stephen L. Moshier
|
|
<moshier@world.std.com> at
|
|
ftp://ftp.std.com/pub/astronomy/selenog.zip. Mr. Sternberg also
|
|
incorporated the algorithm for deltaT, based on code also provided by
|
|
Mr. Moshier. See the comments in deltat.c for full references. My
|
|
greatest thanks to Messrs. Sternberg and Moshier for their generous
|
|
and kind assistance in making XEphem a program of first-class accuracy.</p>
|
|
<p>The improved lunar libration trig series fit to JPL DE403 was
|
|
provided by Stephen L. Moshier, <moshier@world.std.com>.</p>
|
|
<p>Many thanks to Michael Naumann, Michael.Naumann@eso.org, and Miguel
|
|
Albrecht, malbrech@eso.org, at ESO and Tim Kimball, archive@stsci.edu,
|
|
at STScI for their help and support accessing the DSS at their
|
|
institutions. And thanks to ESO and STScI in general for offering this
|
|
service at all.</p>
|
|
<p>Thanks to Seiichi Yoshida, seiichi@muraoka.info.waseda.ac.jp, for
|
|
a subtle fix to the constellation code in 3.1.</p>
|
|
<p>The sample spacecraft elements were furnished by Ron Baalke,
|
|
baalke@jpl.nasa.gov.</p>
|
|
<p>Thanks to Vance Haemmerle, vance@toyvax.Tucson.AZ.US, for his
|
|
updated and appended lists of spacecraft elements, and work on
|
|
improvements to the solar system plotting of long-period trail
|
|
sequences.</p>
|
|
<p>Thanks to Jeroen Valkonet (jeroenv@cvi.ns.nl) for planting the seed
|
|
which grew into the new bitmap clipmask approach of drawing the stars.</p>
|
|
<p>Thanks to Jim Bell, jimbo@cuspif.tn.cornell.edu, and the team at
|
|
Mars Watch for encourage, support and ideas for the first Mars albedo
|
|
map in XEphem. The map as of Version 3.3 is from
|
|
<a target="new" href="http://maps.jpl.nasa.gov/mars.html">http://maps.jpl.nasa.gov/mars.html</a>
|
|
</p>
|
|
<p>Thanks to Dimitromanolakis Apostolos <apdim@grecian.net> for
|
|
his contribution leading to support for fetching DSS in gzipped form.</p>
|
|
<p>Thanks to Miguel Albrecht, malbrech@serv2.hq.eso.org, at ESO for
|
|
his assistance and support of their fine Web access facilities to the
|
|
GSC.</p>
|
|
<p>Rotated trail text uses the xvertext package. Here is the copyright:</p>
|
|
<blockquote> xvertext 5.0, Copyright (c) 1993 Alan Richardson
|
|
(mppa3@uk.ac.sussex.syma)
|
|
<p>Permission to use, copy, modify, and distribute this software
|
|
and its documentation for any purpose and without fee is hereby
|
|
granted, provided that the above copyright notice appear in all
|
|
copies and that both the copyright notice and this permission notice
|
|
appear in supporting documentation. All work developed as a
|
|
consequence of the use of this program should duly acknowledge such
|
|
use. No representations are made about the suitability of this
|
|
software for any purpose. It is provided "as is" without express or
|
|
implied warranty.</p>
|
|
</blockquote>
|
|
IC.edb was submitted by Christos Siopis, siopis@astro.ufl.edu.
|
|
<p>Constellation algorithm is from a paper by Nancy G. Roman,
|
|
"Identification of a constellation from a position", Publications of
|
|
the Astronomical Society of the Pacific, Vol. 99, p. 695-699, July
|
|
1987. Before 3.6 the figures were the work of Chris Marriot. The list
|
|
of
|
|
boundaries is derived from the three files constell.1875.data,
|
|
constell.1875.hdr and constell.doc at
|
|
ftp://explorer.arc.nasa.gov/pub/SPACE/FAQ/.<br>
|
|
</p>
|
|
<p>The WCS solver algorithm technique was inspired by a paper by Frank
|
|
Valdes in PASP, vol 107, page 1119 (1995).<br>
|
|
</p>
|
|
<p>New version of Gemini constellation by Lutz Maendle,
|
|
lmaendle@csi.com.</p>
|
|
<p>Thanks to Dr. Harald Fischer (fischer@vs-ulm.dasa.de) for the GPS
|
|
awk routine and sample position database.</p>
|
|
<p>The high-precision precession routine is from 1989 Astronomical
|
|
Almanac, as interpreted by Craig Counterman. Mr. Counterman also
|
|
deserves the credit for providing the initial encouragement to write
|
|
an astronomical tool specifically for X Windows back in 1990, and for
|
|
significant assistance while developing the heliocentric models.</p>
|
|
<p>The Earth map is derived from data supplied with xearth which
|
|
included the following notice:</p>
|
|
<blockquote> Copyright (C) 1989, 1990, 1993, 1994 Kirk Lauritz Johnson
|
|
<p>Permission to use, copy, modify, distribute, and sell this
|
|
software and its documentation for any purpose is hereby granted
|
|
without fee, provided that the above copyright notice appear in all
|
|
copies and that both that copyright notice and this permission
|
|
notice appear in supporting documentation. The author makes no
|
|
representations about the suitability of this software for any
|
|
purpose. It is provided "as is" without express or implied warranty.</p>
|
|
<p>THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
|
|
INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN
|
|
NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, INDIRECT OR
|
|
CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
|
|
OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
|
|
NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
|
|
WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.</p>
|
|
</blockquote>
|
|
<p>The Earth shaded elevation relief map shipped with XEphem 3.6 is
|
|
from the
|
|
<a href="http://www.ngdc.noaa.gov" target="new">National Geophysical
|
|
Data Center</a>. The one with 3.7.6 is from
|
|
http://www.shadedrelief.com/world_relief/download.html
|
|
</p>
|
|
<p>The pulsar and Radio databases are based on lists supplied by Robert
|
|
Payne, rpayne@nrao.edu. Errors in converting to XEphem are mine.</p>
|
|
<p>The lunar image is based on one I found surfing at:
|
|
ftp://seds.lpl.arizona.edu /pub/images/planets/moon/fullmoon.gif. The
|
|
calculations for the longitude of the terminator and the solar
|
|
altitude are based on the program colong.bas by David Bruning and
|
|
Richard Talcott, published in _Astronomy_, October 1995, page 76.</p>
|
|
<p>Thanks to Richard Clark (rclark@lpl.arizona.edu) for an improved
|
|
version of anomaly.c.</p>
|
|
<p>A great source of comet information is <a target="new"
|
|
href="http://encke.jpl.nasa.gov">http://encke.jpl.nasa.gov</a>
|
|
</p>
|
|
<p>Special thanks to Uwe Bonnes, bon@LTE.E-TECHNIK.uni-erlangen.de,
|
|
and Ralphe Neill, ran@rdt.monash.edu.au, for their many ideas and
|
|
support.</p>
|
|
<p>Many test cases were gleaned from the pages of Sky and Telescope,
|
|
(C) Sky Publishing Corp.</p>
|
|
<p>Many of the sample cities in the "xephem_sites" file are from the
|
|
xsat program, which included the following notice:</p>
|
|
<blockquote> Copyright 1992 by David A. Curry
|
|
<p>Permission to use, copy, modify, distribute, and sell this
|
|
software and its documentation for any purpose is hereby granted
|
|
without fee, provided that the above copyright notice appear in all
|
|
copies and that both that copyright notice and this permission
|
|
notice appear in supporting documentation. The author makes no
|
|
representations about the suitability of this software for any
|
|
purpose. It is provided "as is" without express or implied warranty.</p>
|
|
</blockquote>
|
|
<p>Most of the sample observatories in the "xephem_sites" file are
|
|
transcribed, with permission, from the table beginning on page 28 in
|
|
the July 1993 issue of Sky and Telescope. Any errors in transcription
|
|
are strictly my own.</p>
|
|
<p>Thanks to Lowell Observatory and the Minor Planet Center for
|
|
maintaining their huge lists of asteroids. See
|
|
<a target="new" href="ftp://ftp.lowell.edu/pub/elgb/astorb.html">ftp://ftp.lowell.edu/pub/elgb/astorb.html
|
|
</a> and
|
|
<a target="new" href="http://cfa-www.harvard.edu/cfa/ps/mpc.html">http://cfa-www.harvard.edu/cfa/ps/mpc.html</a>
|
|
, respectively.</p>
|
|
<p>Thanks to the National Space Science Data Center and the Smithsonian
|
|
Astrophysical Observatory for the SAO star catalogue.</p>
|
|
<p>Thanks to the members of the Saguaro Astronomy Club for the
|
|
preparation and free distribution of their deep-sky database. Any
|
|
errors
|
|
in conversion to the .edb format are strictly mine.</p>
|
|
<p>Thanks to Chris Beecroft <aldebaransys@home.com> for his
|
|
encouragement and technical assistance in adding postscript. The
|
|
limited
|
|
results in no way reflect on his capabilities. Initial encouragement
|
|
was
|
|
also received from Frank M. Siegert
|
|
<frank@miranda.tue.schwaben.de>. And thanks to everyone who has
|
|
asked for printing over the years -- I now admit that I like it too!</p>
|
|
<p>Bright stars are based on the 5th Revised edition of the Yale Bright
|
|
Star Catalog, 1991, from
|
|
ftp://adc.gsfc.nasa.gov/pub/adc/archives/catalogs/5/5050. Common names
|
|
supplied by Robert Tidd (inp@violet.berkeley.edu) and Alan Paeth
|
|
(awpaeth@watcgl.waterloo.edu). Any errors in conversion to the .edb
|
|
format are strictly mine.</p>
|
|
<p>I wish to thank all the organizations behind the incredible Internet
|
|
for its maintenance and free and easy access. I also wish to express
|
|
my hope that it retains the spirit of cordial cooperation it fostered
|
|
in its formative years.</p>
|
|
<p>I learned most of what I know of X Windows and Motif programming
|
|
from ICS courses and material found in the various excellent texts
|
|
from O'Reilly & Associates, Inc.</p>
|
|
<p>Thanks to MIT and the X Consortium for inventing, championing and
|
|
maintaining the X Window system, and the various contributing
|
|
organizations to the Open Software Foundation for Motif. Their vision
|
|
of network-aware graphics is still unmatched.</p>
|
|
<p>Similarly, I will be forever indebted to all who contributed to
|
|
UNIX. My passion and appreciation for this remarkable operating system
|
|
matured while I enjoyed four wonderful years at Kitt Peak National
|
|
Observatory (now the National Optical Astronomical Observatory),
|
|
Tucson, AZ, in the early 80's. As with X, UNIX plays a central role in
|
|
my enjoyment of a career in scientific computing.</p>
|
|
<p>It was at KPNO where I met the late Dr. W. Richard Stevens, a fellow
|
|
champion of the elegance of the UNIX architecture, life-long friend
|
|
and mentor.</p>
|
|
<p>Special thanks to all the folks over the years who have provided
|
|
innumerable ideas, suggestions and bug reports, both for XEphem and
|
|
its ancestor, ephem. A major benefit to writing and distributing these
|
|
programs has been the chance to make many friends from around the
|
|
world.</p>
|
|
<p>Elwood Downey ecdowney@ClearSkyInstitute.com</p>
|
|
<p><br>
|
|
<a name="Notes"></a></p>
|
|
<h1><a class="mozTocH1" name="mozTocId402656"></a> 11.0 Notes</h1>
|
|
<h2><a class="mozTocH2" name="mozTocId610542"></a> 11.1 <span
|
|
style="font-weight: bold;">Horizon</span></h2>
|
|
XEphem uses a horizontal plane tangent to the Earth at Elev feet
|
|
above sea level as the horizon for all altitude calculations, rise/set
|
|
events, etc. Due to Earth's curvature, this is not the same as the
|
|
angle up from the local horizon unless the observer is directly on the
|
|
ground. The effect can be found from:<br>
|
|
<div style="margin-left: 40px;"> <span style="font-family: monospace;">sin(a)**2
|
|
= (h**2 + 2Rh) / (R+h)**2</span> </div>
|
|
<br>
|
|
where:<br>
|
|
<div style="margin-left: 40px;"> R = radius of earth<br>
|
|
h = height above ground (same units as R)<br>
|
|
a = increase in altitude </div>
|
|
<br>
|
|
The effect is remarkably significant. For example, it is more than
|
|
two arc minutes at a height of just 5 feet.<br>
|
|
<br>
|
|
<h2><a class="mozTocH2" name="mozTocId730559"></a> 11.2 <span
|
|
style="font-weight: bold;"><a name="glob"></a>glob Patterns<br>
|
|
</span></h2>
|
|
Some of the searches in XEphem can be performed using glob patterns.
|
|
The term glob refers to a limited form of pattern matching (limited
|
|
with respect to the more capable "regular expression") historically
|
|
originating in the UNIX shells for the purposes of specifying a
|
|
collection of file names. In XEphem the glob patterns are implemented
|
|
using the fnmatch() POSIX function. On GNU systems the flag
|
|
FNM_CASEFOLD can be used to make the pattern case insensitive. A glob
|
|
pattern is a set of normal text characters interspersed with any of the
|
|
following special characters known as wildcards:<br>
|
|
<br>
|
|
<table border="1" cellpadding="2" cellspacing="2"
|
|
width="585">
|
|
<tbody>
|
|
<tr>
|
|
<td valign="top"><b>glob wildcard</b><br>
|
|
</td>
|
|
<td valign="top"><b>Meaning</b><br>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td valign="top">
|
|
<blockquote>?<br>
|
|
</blockquote>
|
|
</td>
|
|
<td valign="top">matches exactly one character</td>
|
|
</tr>
|
|
<tr>
|
|
<td valign="top">
|
|
<blockquote>*<br>
|
|
</blockquote>
|
|
</td>
|
|
<td valign="top">matches zero or more characters</td>
|
|
</tr>
|
|
<tr>
|
|
<td valign="top">
|
|
<blockquote>[abc]<br>
|
|
</blockquote>
|
|
</td>
|
|
<td valign="top">matches any one of the specified characters. A
|
|
pair of
|
|
characters separated by a hyphen denotes a range expression such that
|
|
any character that sorts between those two characters, inclusive,
|
|
is matched. If the first character following the [ is a ! or a ^
|
|
then any character <i>not</i> enclosed is matched.</td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
<br>
|
|
For example, if a list of candidates consists of the following:<br>
|
|
<br>
|
|
abc<br>
|
|
aabc<br>
|
|
abbc<br>
|
|
acc<br>
|
|
adc<br>
|
|
<br>
|
|
then the pattern a* matches all; ab* matches abc and abbc; a[ac]*
|
|
matches aabc and abbc; a?c matches abc, acc and adc; a[a-c]c matches
|
|
abc and acc; a[^a-c]c matches adc; and *b* matches abc, aabc and abbc.<br>
|
|
<br>
|
|
<h2><a class="mozTocH2" name="mozTocId730558"></a> 11.3 <span
|
|
style="font-weight: bold;">Accuracy</span></h2>
|
|
In the period 1689 through 2247 Jupiter and beyond use CHAPRONT J.,
|
|
Astron. Astrophys. Suppl. Ser. 109, 181 (1995), otherwise all planetary
|
|
ephemerides except Pluto use VSOP87 from Bretagnon P., Francou G.,
|
|
Astron. Astrophys. 202, 309 (1988). Compared with JPL DE200 for
|
|
Mercury, Venus and Mars the accuracy of this model rises to 1" at the
|
|
ends of the year range 2000 +/- 4000. For Jupiter and Saturn, the 1"
|
|
range is 2000 +/- 2000. For Uranus and Neptune, it is 2000 +/- 6000.<br>
|
|
<br>
|
|
Lunar ephemerides are from S. L. Moshier, December, 1996, available
|
|
from ftp://ftp.std.com/pub/astronomy/selenog.zip. Compared with JPL
|
|
DE404 the accuracy is better than 0.5" for the period -1369 to +2950.<br>
|
|
<br>
|
|
Other heliocentric objects are well within one arc minute at the time
|
|
of the epoch of their elements; this steadily worsens with time since
|
|
XEphem does not apply perturbations.<br>
|
|
<br>
|
|
Using a GPS position locator and transit, I have independently verified
|
|
Sun and Moon limb rise and set times are accurate to within one minute
|
|
and azimuths are within about 0.1 degree.<br>
|
|
<br>
|
|
The natural satellite model from BDL used for 1999-2010 is stated as
|
|
good to 1/2 arcsecond accuracy. In my tests against JPL DE405 I would
|
|
say this is true about 50% of the time, with a worst case of about 4
|
|
AS.<br>
|
|
<br>
|
|
<h2><a class="mozTocH2" name="mozTocId118721"></a> 11.4 <span
|
|
style="font-weight: bold;">TODO</span></h2>
|
|
The following is the current list of future ideas for XEphem. Thanks
|
|
to all who have made suggestions. Please let me know your priorities
|
|
or suggest more.<br>
|
|
<ul>
|
|
<li>write a tool to find g/k from a set of predicted magnitudes.</li>
|
|
<li>display occultation path between *any* two objects in the Earth
|
|
view</li>
|
|
<li>add sidereal day and month trail intervals.</li>
|
|
<li>just label month and year tickmarks in trails when they change</li>
|
|
<li>comet tail pointer</li>
|
|
<li>meteor showers, (dedalus)</li>
|
|
<li>Iridium flares </li>
|
|
<li>option for rise/set info to be Today or Next. </li>
|
|
<li>add "Plot JD as date" to plot display</li>
|
|
<li>use better earth shape model </li>
|
|
<li>add T » F and F » T to Binary</li>
|
|
<li>use user-defined horizon for rise/set calculations</li>
|
|
<li>way to repeat the Solver for more solutions, as in "solver in a
|
|
loop" </li>
|
|
<li>expand .edb to capture real variables</li>
|
|
<li>more hot-keys</li>
|
|
<li>month of lunar phases </li>
|
|
<li>Jup and Sat moon timelines and events, ala S&T </li>
|
|
<li>separate Telescope view window </li>
|
|
<li>connect trails with spline not just line segments </li>
|
|
<li>direct connections to Simbad and NED </li>
|
|
<li>plot in polar coords </li>
|
|
<li>automatic initial Go</li>
|
|
<li>topocentric lunations </li>
|
|
<li>individual control over trails in sol system </li>
|
|
<li>provide a means to save and install multiple color+font schemes.</li>
|
|
<li>tool to generate MPC astrometric report</li>
|
|
<li>draggable eyepieces</li>
|
|
<li>text entry fields to allow higher-precision eyepiece size and PA</li>
|
|
</ul>
|
|
<h2><a class="mozTocH2" name="mozTocId982160"></a> 11.5 <span
|
|
style="font-weight: bold;">Known Bugs</span></h2>
|
|
<ul>
|
|
<li>Preferences » Time Zone does not update dates of FM/NM if
|
|
they happen
|
|
to squirm. </li>
|
|
<li>length of night wrong when savings time causes dusk after
|
|
midnight </li>
|
|
<li>center constellation names based on boundaries rather than on
|
|
figures</li>
|
|
<li>solar trails don't account for long-term (10's of years)
|
|
precession </li>
|
|
<li>plot's View settings are not Saveable. </li>
|
|
<li>figure out calendar prior to Oct 1752.</li>
|
|
<li>Sky View trails are not always clipped properly against a user-defined
|
|
horizon </li>
|
|
<li>The visual magnitudes for all solar system bodies except the
|
|
planets do not take into account the phase.</li>
|
|
<li>Changing equinox or geo/topo then update, moon view tables do not
|
|
update.</li>
|
|
<li>Time not correct when system set to POSIX time</li>
|
|
<li>Earth satellites are not plotted in Sky View correctly in
|
|
geocentric&altaz mode (use geocentric&radec mode). <br>
|
|
</li>
|
|
</ul>
|
|
<h2><a class="mozTocH2" name="mozTocId866585"></a> 11.6 History</h2>
|
|
In 1981 I purchased a genuine IBM PC. Soon I was building a character
|
|
oriented program in C for DOS that displayed ephemeris data, packing as
|
|
much as possible on the character-based 24x80 display. That program was
|
|
called <span style="font-style: italic;">ephem</span> because it was
|
|
as much of the
|
|
word <span style="font-style: italic;">ephemeris</span> that would fit
|
|
in 8 characters and still retain some sensible meaning. I was using
|
|
UNIX at work
|
|
so
|
|
I made sure it would run there too using the <i>curses</i> library. In
|
|
1989 I took a course in Motif. By 1990 it seemed to
|
|
have won the UNIX desktop wars so I started converting <i>ephem</i> to
|
|
Motif+UNIX. The convention for naming X Window System programs was to
|
|
add an <span style="font-style: italic;">x</span> prefix so that
|
|
program
|
|
was named <span style="font-style: italic;">xephem</span>. I have been
|
|
diddling with it ever since. The original <span
|
|
style="font-style: italic;">ephem</span> is still <a
|
|
href="http://www.clearskyinstitute.com/ephem/ephem-4.29.tar.gz">available</a>.<br>
|
|
</body>
|
|
</html>
|