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#!/usr/bin/env perl
use FileHandle;
# Ed Murphy's program to rewrite the orbit page
# Updated 03/27/00 Changed GSOC to Heavens Above
$output_filename = "/data2/violet/htdocs/users/orbit.html";
open (OUTF, ">$output_filename") || die "Cannot open $output_filename file";
system("chmod ug+rw $output_filename");
system("chgrp www $output_filename");
$input_filename = "@DATADIR@/calfiles/FUSE.TLE";
open (INP_TLE, "<$input_filename") || die "Cannot open $input_filename file";
$satid = 25791;
&input_lines;
close (INP_TLE);
&parse_lines;
&convert_doy;
&convert_dayfrac;
&calculate_a0;
&calculate_orbs;
$now=`date`;
$datest = substr($now,4,3)." ".substr($now,8,2).", ".substr($now,24,4);
print OUTF "<HTML>\n";
print OUTF "<HEAD>\n";
print OUTF "<title>FUSE Orbital Elements page</title>\n";
print OUTF "</HEAD>\n";
print OUTF "<BODY bgcolor=#ffffff ALINK=\"#000000\" VLINK=\"darkblue\">\n";
print OUTF "<center>\n";
print OUTF "<table width=640>\n";
print OUTF "<tr><td>\n";
print OUTF "<img src=\"/figures/purple_line2.gif\" width=640>\n";
print OUTF "<table cellpadding=5 cellspacing=5 width=550>\n";
print OUTF "<tr>\n";
print OUTF "<td valign=top align=left>\n";
print OUTF "<img src=\"/figures/andromeda_moo_small.gif\">\n";
print OUTF "</td>\n";
print OUTF "<td valign=top align=left>\n";
print OUTF "<font size=+3><font color=\"#6666CC\">\n";
print OUTF "<b>FUSE<P>\n";
print OUTF "<i>Orbital Elements</font></font></i></b>\n";
print OUTF "</td>\n";
print OUTF "</tr>\n";
print OUTF "</table>\n";
print OUTF "<img src=\"/figures/purple_line2.gif\" width=640>\n";
print OUTF "<p>\n";
print OUTF "<center>\n";
print OUTF "<font color=\"#CC0099\" size=4><b>\n";
print OUTF "Where is FUSE now?<br></b></font>\n";
print OUTF "<font size=4>Check out the\n";
print OUTF "<a href=\"http://www.heavens-above.com/orbitdisplay.asp?lat=39.3&lng=-76.6&loc=BALTIMORE&TZ=EST&satid=25791\" >\n";
print OUTF "Heavens-Above Satellite Predictions page </a></font>.\n";
print OUTF "</center>\n";
print OUTF "<P>\n";
print OUTF "<hr>\n";
print OUTF "<p><pre>\n";
print OUTF " \n";
print OUTF "FUSE orbital elements:\n";
print OUTF " NORAD number 25791\n";
print OUTF " International ID 99035A\n";
print OUTF " \n";
&print_orb;
print OUTF "</pre>\n";
&print_tail;
close (OUTF);
### end of Perl script
sub convert_doy {
@daytab1 = (0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31);
@daytab2 = (0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31);
@monthstr = ("", "January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December");
if ((($year%4 == 0) && ($year%100 != 0)) || ($year%400 == 0)) {
# $year is a leap year use daytab1
for ($i = 1; $doy > $daytab1[$i]; $i++) {
$doy -= $daytab1[$i];
}
} else {
# $year is not a leap year, use daytab2
for ($i = 1; $doy > $daytab2[$i]; $i++) {
$doy -= $daytab2[$i];
}
}
$month = $monthstr[$i];
$day = $doy;
}
sub convert_dayfrac {
$dayfrac *= 24.0;
$hour = int($dayfrac);
$minute = int(($dayfrac-$hour)*60.0);
$second = ((($dayfrac-$hour)*60.0)-$minute)*60.0;
}
sub input_lines {
$line1 = <INP_TLE>;
$line2 = <INP_TLE>;
$line3 = <INP_TLE>;
$id2 = substr($line2, 2, 5);
$id3 = substr($line3, 2, 5);
if (($id2 != $satid) || ($id3 != $satid)) {
print STDOUT "Error in TLE:\n";
print STDOUT $line1;
print STDOUT $line2;
print STDOUT $line3;
# die "Error in TLE";
}
}
sub parse_lines {
$year = substr($line2, 18, 2);
$doy = substr($line2, 20, 3);
$dayfrac = substr($line2, 23, 9);
$epoch = $year.$doy.$dayfrac;
$incl = substr($line3, 9, 8);
$raan = substr($line3, 17,8);
$eccen = substr($line3, 26, 7);
$eccen = "0." . $eccen;
$mean_mot = substr($line3, 52, 11);
$mean_anom = substr($line3, 43, 8);
$arg_perig = substr($line3, 34, 8);
if ($year > 50) {
$year += 1900;
} else {
$year += 2000;
}
$dayfrac = "0".$dayfrac;
}
sub calculate_a0 {
$mu = 3.986005E5;
$pi = 3.14159265358979;
$radian = 0.0174532925200;
$mm=2.0*$pi*$mean_mot/(24.0*60.0);
$ke=0.74366916E-1;
$k2=5.413080E-4;
$a1=($ke/$mm)**(2.0/3.0);
$inrad = $incl * $radian;
$d1=3.0/2.0*$k2/($a1*$a1)*(3.0*cos($inrad)*cos($inrad)-1.0)/((1.0-$eccen*$eccen)**(3.0/2.0));
$a0=$a1*(1.0-$d1/3.0-$d1*$d1-134.0/81.0*$d1*$d1*$d1);
$d0=3.0/2.0*$k2/($a0*$a0)*(3.0*cos($inrad)*cos($inrad)-1.0)/((1.0-$eccen*$eccen)**(3.0/2.0));
$semiax=$a0/(1-$d0)*6378.135;
}
sub calculate_orbs {
$period = 60.0*24.0/($mean_mot/(1+$d0));
$cax=$eccen*$semiax;
$perigee=$semiax-$cax-6378.1;
$apogee=$semiax+$cax-6378.1;
}
sub print_orb {
print OUTF " Epoch $epoch\n";
printf OUTF " Semimajor axis %7.2f km\n",$semiax;
printf OUTF " Apogee %5.2f km\n",$apogee;
printf OUTF " Perigee %5.2f km\n",$perigee;
print OUTF " Eccentricity $eccen\n";
printf OUTF " Inclination %6.2f degrees\n",$incl;
printf OUTF " Period %6.2f minutes\n",$period;
printf OUTF " RA of asc. node %6.2f degrees\n",$raan;
printf OUTF " Arg. of perigee %6.2f degrees\n",$arg_perig;
printf OUTF " Mean anomaly %6.2f degrees\n",$mean_anom;
print OUTF " \n";
}
sub print_tail {
print OUTF "<p>";
print OUTF "The FUSE Delta II second stage (NORAD #25792) reentered on \n";
print OUTF "the morning of August 4, 1999 during orbit number 708. \n";
print OUTF "According to predictions by Alan Pickup, reentry \n";
print OUTF "occured within 90 minutes of 5:31 UT, probably over the \n";
print OUTF "Arabian Sea or India. The final orbit was 119 x 103 km (74 x 64 mi).\n";
print OUTF "<p>";
print OUTF "<center>";
print OUTF "<font size=+2><font color=\"#6666CC\">\n";
print OUTF "<a href=\"reentry.html\"> Could anything have survived reentry?</a></font></font><p>\n";
print OUTF "</center>";
print OUTF "<img align=center src=\"delta2decay.gif\">\n";
print OUTF "<P>These numbers assume a Keplerian orbit; the actual apogee and perigee \n";
print OUTF "will differ by a few km on an orbit-to-orbit basis.\n";
print OUTF "<p>";
print OUTF "<p>The NORAD Two-Line Elements (TLEs) for FUSE can be found in the file \n";
print OUTF "<a href=\"./FUSE.TLE\" > FUSE.TLE </A>.\n";
print OUTF "<p> \n";
print OUTF "This page is automatically updated daily. I wish to thank \n";
print OUTF "<a href=\"mailto:deej\@deej.com\">Doyle Groves</a> \n";
print OUTF "for providing a Perl script to access the NASA\n";
print OUTF "Orbital Information Group web page.\n";
print OUTF "<p> Ed Murphy, <a href=\"mailto:emurphy\@pha.jhu.edu\">\n";
print OUTF "<address>emurphy\@pha.jhu.edu</address></a>\n";
print OUTF "<P>\n";
print OUTF "<img src=\"/figures/purple_line2.gif\" width=640>\n";
print OUTF "<P>\n";
print OUTF "Last changed: $datest.\n";
print OUTF "<P>\n";
print OUTF "<i><a href=\"/index.shtml\">Return to the FUSE home page.</a></i><br clear=left>\n";
print OUTF "<p>\n";
print OUTF "</td></tr>\n";
print OUTF "</table>\n";
print OUTF "</center>\n";
print OUTF "</BODY>\n";
print OUTF "</HTML>\n";
}
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