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
2461304.5
0.080451388889
-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 = +76 sec = +00h 01m 16s
Double-Click Within Text Area to Select ALL Text
SIDEREAL TIME FOR GIVEN DATE, TIME AND LONGITUDE Local Date = 2026 Sep 21 [Monday] Gregorian JD Number = 2461305 JD00 = 2461304.5 = JD for 00h of date Local Time = 01:55:51 = 0.080451388889 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) = 2461304.788784722222 Longitude = -76° 49' 23.915" = -76.8233097222° (W) = -05h 07m 17.594s = -5.1215539815 h ================================================================= Local Mean Sidereal Time at Longitude -76.8233097222° (W) 01h 49m 14.387s = 1.8206631732 h 27° 18' 35.81" = 27.3099475978° Local True Sidereal Time at Longitude = -76.8233097222° (W) 01h 49m 14.936s = 1.8208155457 h 27° 18' 44.04" = 27.3122331854° Greenwich Mean Sidereal Time 06h 56m 31.982s = 6.9422171547 h 104° 07' 59.726" = 104.1332573201° Greenwich True Sidereal Time 06h 56m 32.530s = 6.9423695272 h 104° 08' 07.954" = 104.1355429078° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.267208454064 Julian centuries reckoned from J2000.0 t = 0.026720845406 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) +8.968" = +0.0024911303° = Nutation in ecliptical longitude +8.289" = +0.0023025907° = Nutation in ecliptical obliquity +0.549s = +0.0022855877° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 08.940" = 23.4358167184° Nutation in Obliquity +8.289" = +0.0023025907° True Ecliptic Obliquity 23° 26' 17.230" = 23.4381193092°
Jay Tanner - PHP Science Labs - 2026 - 1.7