Sidereal Time Calculator For Any Date, Time and Longitude
PHP Program by Jay Tanner
Local Date
±
Y M D (Neg=BC)
Local Time
HH MM SS (00 to 24h)
Local Time Zone Offset
HH MM (Neg/Pos = W/E)
ΔT (Delta T)
±
HMS
UT
2461012.5
0.254120370370
-0.208333333333
+0.000000000000
Calendar Mode:
Julian
Gregorian
Longitude:
±Deg.ddd or ±D M S (Neg=W)
-76.8233097222
IMPORTANT:
Make sure that the local time, time zone and longitude are correctly matched for the location.
OPTIONAL:
NASA Polynomial ΔT estimate = +75 sec = +00h 01m 15s
Double-Click Within Text Area to Select ALL Text
SIDEREAL TIME FOR GIVEN DATE, TIME AND LONGITUDE Local Date = 2025 Dec 03 [Wednesday] Gregorian JD Number = 2461013 JD00 = 2461012.5 = JD for 00h of date Local Time = 06:05:56 = 0.254120370370 day T Zone Diff = -05:00 = -0.208333333333 day Delta T = +00:00:00 = +0.000000000000 day Astronomical Julian Date: JDTT = JDNum - 0.5 + LTFrac - (TZFrac) + (dTFrac) = 2461012.962453703703 Longitude = -76° 49' 23.915" = -76.8233097222° (W) = -05h 07m 17.594s = -5.1215539815 h ================================================================= Local Mean Sidereal Time at Longitude -76.8233097222° (W) 10h 48m 46.302s = 10.8128616489 h 162° 11' 34.53" = 162.1929247342° Local True Sidereal Time at Longitude = -76.8233097222° (W) 10h 48m 46.519s = 10.8129219486 h 162° 11' 37.78" = 162.1938292290° Greenwich Mean Sidereal Time 15h 56m 03.896s = 15.9344156304 h 239° 00' 58.444" = 239.0162344566° Greenwich True Sidereal Time 15h 56m 04.113s = 15.9344759301 h 239° 01' 01.700" = 239.0171389514° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.259218684564 Julian centuries reckoned from J2000.0 t = 0.025921868456 Julian millennia reckoned from J2000.0 Circular Trig Functions of Given Longitude Longitude = -76.8233097222° (W) sin(Lon) = -0.973671722605411 cos(Lon) = +0.227954768756023 tan(Lon) = -4.271337370649689 Nutations (IAU 2000B Series) +3.549" = +0.0009858367° = Nutation in ecliptical longitude +8.275" = +0.0022985381° = Nutation in ecliptical obliquity +0.217s = +0.0009044948° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 09.314" = 23.4359206053° Nutation in Obliquity +8.275" = +0.0022985381° True Ecliptic Obliquity 23° 26' 17.589" = 23.4382191434°
Jay Tanner - PHP Science Labs - 2025 - 1.7