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
2461234.5
0.654849537037
-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 Jul 13 [Monday] Gregorian JD Number = 2461235 JD00 = 2461234.5 = JD for 00h of date Local Time = 15:42:59 = 0.654849537037 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) = 2461235.36318287037 Longitude = -76° 49' 23.915" = -76.8233097222° (W) = -05h 07m 17.594s = -5.1215539815 h ================================================================= Local Mean Sidereal Time at Longitude -76.8233097222° (W) 11h 02m 39.389s = 11.0442745881 h 165° 39' 50.83" = 165.6641188208° Local True Sidereal Time at Longitude = -76.8233097222° (W) 11h 02m 39.936s = 11.0444266720 h 165° 39' 59.04" = 165.6664000794° Greenwich Mean Sidereal Time 16h 09m 56.983s = 16.1658285695 h 242° 29' 14.743" = 242.4874285432° Greenwich True Sidereal Time 16h 09m 57.530s = 16.1659806535 h 242° 29' 22.955" = 242.4897098018° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.265307684678 Julian centuries reckoned from J2000.0 t = 0.026530768467 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) +8.951" = +0.0024864085° = Nutation in ecliptical longitude +7.546" = +0.0020961783° = Nutation in ecliptical obliquity +0.548s = +0.0022812586° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 09.029" = 23.4358414332° Nutation in Obliquity +7.546" = +0.0020961783° True Ecliptic Obliquity 23° 26' 16.575" = 23.4379376115°
Jay Tanner - PHP Science Labs - 2026 - 1.7