mirror of https://github.com/XEphem/XEphem.git
135 lines
3.4 KiB
Perl
Executable File
135 lines
3.4 KiB
Perl
Executable File
#!/usr/bin/perl
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# read Soft00Cmt.txt on stdin and generate two files. The name of the files
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# is $1.edb and $1_dim.edb, where $1 refers to the first (and only) argument
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# to this script.
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#
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# $1.edb will contain only those comets which might ever be brighter than
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# $dimmag (set below); the remaining comets are saved in $1_dim.edb.
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#
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# Soft00Cmt.txt is a service of the Minor Planet Center,
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# http://cfa-www.harvard.edu/iau/Ephemerides/Comets/Soft00Cmt.txt
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#
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# Copyright (c) 2000 Elwood Downey
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# grab RCS version
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$ver = '$Revision: 1.3 $';
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$ver =~ s/\$//g;
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# setup cutoff mag
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$dimmag = 13; # dimmest mag to be saved in "bright" file
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# require exactly one arg
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&usage() if (@ARGV != 1 or $ARGV[0] eq "-help");
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# create files
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$fnbase = $ARGV[0];
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$brtfn = "$fnbase.edb"; # name of file for bright comets
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open BRT, ">$brtfn" or die "Can not create $brtfn\n";
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$dimfn = "$fnbase"."_dim.edb";# name of file for dim comets
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open DIM, ">$dimfn" or die "Can not create $dimfn\n";
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# build some common boilerplate
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($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = gmtime;
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$year += 1900;
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$mon += 1;
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$from = "# Data is from http://cfa-www.harvard.edu/iau/Ephemerides/Comets\n";
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$what = "# Generated by mpccomet2edb.pl $ver, (c) 2000 Elwood Downey\n";
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$when = "# Processed $year-$mon-$mday $hour:$min:$sec UTC\n";
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# add boilerplate to each file
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print BRT "# Comets ever brighter than $dimmag.\n";
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print BRT $from;
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print BRT $what;
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print BRT $when;
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print DIM "# Comets never brighter than $dimmag.\n";
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print DIM $from;
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print DIM $what;
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print DIM $when;
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# process each Soft00Cmt.txt entry
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while (<STDIN>) {
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chomp();
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next if (length() < 100);
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# build the name
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$name = &s(103, length());
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$name =~ s/[\(\)]//g;
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$name =~ s/^ *//;
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$name =~ s/ *$//;
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next if ($name eq "");
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# gather the orbital params
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$i = &s(71,79) + 0;
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$O = &s(61,69) + 0;
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$o = &s(51,59) + 0;
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$q = &s(31,39) + 0;
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$e = &s(41,49) + 0;
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$M = 0;
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$E = &s(20,21) . "/" . &s(23,29) . "/" . &s(15,18); # Y/M/D
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$E =~ s/ //g;
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$H = &s(97,100) + 0;
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$G = &s(91,95) + 0;
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# decide whether it's ever brighter than $dimmag
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$aph = $e == 1 ? $q : $q*(1+$e)/(1-$e);
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if ($q < 1.1 && $aph > .9) {
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$fd = BRT; # might be in the back yard some day :-)
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} else {
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$maxmag = $H + 5*&log10($q*&absv($q-1));
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$fd = $maxmag > $dimmag ? DIM : BRT;
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}
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# print, depending on eccentricity
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if ($e < .99) {
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# elliptical orbit
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# better to avoid if e is getting very close to 1
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$a = $q/(1-$e);
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print $fd "$name,e,$i,$O,$o,$a,0,$e,$M,$E,2000.0,$H,$G\n";
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} elsif ($e > 1) {
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# hyperbolic orbit
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print $fd "$name,h,$E,$i,$O,$o,$e,$q,2000.0,$H,$G\n";
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} else {
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# parabolic orbit
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print $fd "$name,p,$E,$i,$o,$q,$O,2000.0,$H,$G\n";
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}
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}
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# like substr($_,first,last), but one-based.
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sub s
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{
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substr ($_, $_[0]-1, $_[1]-$_[0]+1);
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}
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# return log base 10
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sub log10
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{
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.43429*log($_[0]);
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}
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# return absolute value
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sub absv
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{
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$_[0] < 0 ? -$_[0] : $_[0];
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}
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# return min of two values
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sub min
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{
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$_[0] < $_[1] ? $_[0] : $_[1];
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}
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# print usage message then die
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sub usage
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{
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print "Usage: $0 <base> < Soft00Cmt.txt\n";
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print "$ver\n";
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print "Purpose: convert Soft00Cmt.txt file to .edb format.\n";
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print "Creates two files:\n";
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print " <base>.edb: all comets ever brighter than $dimmag\n";
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print " <base>_dim.edb: all comets never brighter than $dimmag\n";
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print "Nothing occurs on our stdout and stderr except error messages.\n";
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exit 1;
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}
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