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
2461021.5
0.699664351852
-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 12 [Friday] Gregorian JD Number = 2461022 JD00 = 2461021.5 = JD for 00h of date Local Time = 16:47:31 = 0.699664351852 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) = 2461022.407997685185 Longitude = -76° 49' 23.915" = -76.8233097222° (W) = -05h 07m 17.594s = -5.1215539815 h ================================================================= Local Mean Sidereal Time at Longitude -76.8233097222° (W) 22h 07m 35.696s = 22.1265822367 h 331° 53' 55.44" = 331.8987335511° Local True Sidereal Time at Longitude = -76.8233097222° (W) 22h 07m 35.970s = 22.1266583256 h 331° 53' 59.55" = 331.8998748836° Greenwich Mean Sidereal Time 03h 14m 53.290s = 3.2481362182 h 48° 43' 19.356" = 48.7220432735° Greenwich True Sidereal Time 03h 14m 53.564s = 3.2482123071 h 48° 43' 23.465" = 48.7231846059° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.259477289464 Julian centuries reckoned from J2000.0 t = 0.025947728946 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) +4.478" = +0.0012439733° = Nutation in ecliptical longitude +8.306" = +0.0023071896° = Nutation in ecliptical obliquity +0.274s = +0.0011413324° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 09.302" = 23.4359172428° Nutation in Obliquity +8.306" = +0.0023071896° True Ecliptic Obliquity 23° 26' 17.608" = 23.4382244324°
Jay Tanner - PHP Science Labs - 2025 - 1.7