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
2460912.5
0.915636574074
-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 Aug 25 [Monday] Gregorian JD Number = 2460913 JD00 = 2460912.5 = JD for 00h of date Local Time = 21:58:31 = 0.915636574074 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) = 2460913.623969907407 Longitude = -76° 49' 23.915" = -76.8233097222° (W) = -05h 07m 17.594s = -5.1215539815 h ================================================================= Local Mean Sidereal Time at Longitude -76.8233097222° (W) 20h 09m 42.250s = 20.1617361694 h 302° 25' 33.75" = 302.4260425409° Local True Sidereal Time at Longitude = -76.8233097222° (W) 20h 09m 42.503s = 20.1618062769 h 302° 25' 37.54" = 302.4270941534° Greenwich Mean Sidereal Time 01h 16m 59.845s = 1.2832901509 h 19° 14' 57.668" = 19.2493522633° Greenwich True Sidereal Time 01h 17m 00.097s = 1.2833602584 h 19° 15' 01.454" = 19.2504038757° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.256498945103 Julian centuries reckoned from J2000.0 t = 0.025649894510 Julian millennia reckoned from J2000.0 Nutations (IAU 2000B Series) +4.126" = +0.0011461877° = Nutation in ecliptical longitude +9.391" = +0.0026086675° = Nutation in ecliptical obliquity +0.252s = +0.0010516124° = Equation of the equinoxes Mean Obliquity of the Ecliptic 23° 26' 09.441" = 23.4359559687° True Obliquity of the Ecliptic 23° 26' 18.833" = 23.4385646362°
Jay Tanner - PHP Science Labs - 2025 - 1.7