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## JD to Local/Greenwich Sidreal Time
## http://www.jgiesen.de/astro/astroJS/sunriseJS/index.htm // in
rsTL.js
##
function jd2lst($JD, $longit=0)
{
$MJD = $JD - 2400000.5;
$MJD0 = floor($MJD);
$ut = ($MJD - $MJD0) * 24.0;
$t = ($MJD0 - 51544.5) / 36525.0;
$gst = 6.697374558 + (1.00273790935*$ut) + (8640184.812866 +
(0.093104-0.0000062*$t)*$t) * $t/3600.0;
$gst = ($gst>=0) ? fmod($gst,24.0) : fmod($gst,24.0) + 24.0; // to 24hours unit
$lst = fmod($gst+$longit/15.0,24.0); // to 24hours unit
return $lst; // 24hours unit (hour angle)
}
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