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
2460972.5
0.867384259259
-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 Oct 24 [Friday] Gregorian JD Number = 2460973 JD00 = 2460972.5 = JD for 00h of date Local Time = 20:49:02 = 0.867384259259 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) = 2460973.575717592592 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 56m 35.158s = 22.9430994502 h 344° 08' 47.37" = 344.1464917529° Local True Sidereal Time at Longitude = -76.8233097222° (W) 22h 56m 35.319s = 22.9431440380 h 344° 08' 49.78" = 344.1471605701° Greenwich Mean Sidereal Time 04h 03m 52.752s = 4.0646534317 h 60° 58' 11.285" = 60.9698014753° Greenwich True Sidereal Time 04h 03m 52.913s = 4.0646980195 h 60° 58' 13.693" = 60.9704702924° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.258140334499 Julian centuries reckoned from J2000.0 t = 0.025814033449 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) +2.624" = +0.0007289655° = Nutation in ecliptical longitude +9.010" = +0.0025028346° = Nutation in ecliptical obliquity +0.161s = +0.0006688171° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 09.365" = 23.4359346266° Nutation in Obliquity +9.010" = +0.0025028346° True Ecliptic Obliquity 23° 26' 18.375" = 23.4384374611°
Jay Tanner - PHP Science Labs - 2025 - 1.7