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
2460873.5
0.050520833333
-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 Jul 17 [Thursday] Gregorian JD Number = 2460874 JD00 = 2460873.5 = JD for 00h of date Local Time = 01:12:45 = 0.050520833333 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) = 2460873.758854166666 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 46m 45.943s = 20.7794286199 h 311° 41' 29.14" = 311.6914292988° Local True Sidereal Time at Longitude = -76.8233097222° (W) 20h 46m 46.150s = 20.7794861368 h 311° 41' 32.25" = 311.6922920527° Greenwich Mean Sidereal Time 01h 54m 03.537s = 1.9009826014 h 28° 30' 53.060" = 28.5147390212° Greenwich True Sidereal Time 01h 54m 03.744s = 1.9010401183 h 28° 30' 56.166" = 28.5156017751° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.255407497718 Julian centuries reckoned from J2000.0 t = 0.025540749771 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) +3.385" = +0.0009403433° = Nutation in ecliptical longitude +8.749" = +0.0024301646° = Nutation in ecliptical obliquity +0.207s = +0.0008627539° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 09.493" = 23.4359701603° Nutation in Obliquity +8.749" = +0.0024301646° True Ecliptic Obliquity 23° 26' 18.241" = 23.4384003249°
Jay Tanner - PHP Science Labs - 2025 - 1.7