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
2461154.5
0.657777777778
-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 = 2026 Apr 24 [Friday] Gregorian JD Number = 2461155 JD00 = 2461154.5 = JD for 00h of date Local Time = 15:47:12 = 0.657777777778 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) = 2461155.366111111111 Longitude = -76° 49' 23.915" = -76.8233097222° (W) = -05h 07m 17.594s = -5.1215539815 h ================================================================= Local Mean Sidereal Time at Longitude -76.8233097222° (W) 05h 51m 28.652s = 5.8579587953 h 87° 52' 09.78" = 87.8693819302° Local True Sidereal Time at Longitude = -76.8233097222° (W) 05h 51m 29.024s = 5.8580621672 h 87° 52' 15.36" = 87.8709325074° Greenwich Mean Sidereal Time 10h 58m 46.246s = 10.9795127768 h 164° 41' 33.690" = 164.6926916526° Greenwich True Sidereal Time 10h 58m 46.618s = 10.9796161486 h 164° 41' 39.272" = 164.6942422297° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.263117484219 Julian centuries reckoned from J2000.0 t = 0.026311748421 Julian millennia reckoned from J2000.0 Nutations (IAU 2000B Series) +6.084" = +0.0016900221° = Nutation in ecliptical longitude +8.562" = +0.0023784408° = Nutation in ecliptical obliquity +0.372s = +0.0015505772° = Equation of the equinoxes Mean Obliquity of the Ecliptic 23° 26' 09.132" = 23.4358699112° True Obliquity of the Ecliptic 23° 26' 17.694" = 23.4382483520°
Jay Tanner - PHP Science Labs - 2026 - 1.7