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
2460924.5
0.187060185185
-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 Sep 06 [Saturday] Gregorian JD Number = 2460925 JD00 = 2460924.5 = JD for 00h of date Local Time = 04:29:22 = 0.187060185185 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) = 2460924.895393518518 Longitude = -76° 49' 23.915" = -76.8233097222° (W) = -05h 07m 17.594s = -5.1215539815 h ================================================================= Local Mean Sidereal Time at Longitude -76.8233097222° (W) 03h 24m 59.566s = 3.4165461117 h 51° 14' 53.49" = 51.2481916761° Local True Sidereal Time at Longitude = -76.8233097222° (W) 03h 24m 59.818s = 3.4166160193 h 51° 14' 57.27" = 51.2492402899° Greenwich Mean Sidereal Time 08h 32m 17.160s = 8.5381000932 h 128° 04' 17.405" = 128.0715013985° Greenwich True Sidereal Time 08h 32m 17.412s = 8.5381700008 h 128° 04' 21.180" = 128.0725500123° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.256807539863 Julian centuries reckoned from J2000.0 t = 0.025680753986 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) +4.115" = +0.0011429196° = Nutation in ecliptical longitude +9.464" = +0.0026289817° = Nutation in ecliptical obliquity +0.252s = +0.0010486138° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 09.427" = 23.4359519562° Nutation in Obliquity +9.464" = +0.0026289817° True Ecliptic Obliquity 23° 26' 18.891" = 23.4385809379°
Jay Tanner - PHP Science Labs - 2025 - 1.7