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
0.050034722222
-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 = 01:12:03 = 0.050034722222 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) = 2460873.758368055555 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 03.828s = 20.7677300072 h 311° 30' 57.42" = 311.5159501080° Local True Sidereal Time at Longitude = -76.8233097222° (W) 20h 46m 04.035s = 20.7677875247 h 311° 31' 00.53" = 311.5168128698° Greenwich Mean Sidereal Time 01h 53m 21.422s = 1.8892839887 h 28° 20' 21.335" = 28.3392598303° Greenwich True Sidereal Time 01h 53m 21.629s = 1.8893415061 h 28° 20' 24.441" = 28.3401225922° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.255407484409 Julian centuries reckoned from J2000.0 t = 0.025540748440 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" = +0.0009403519° = Nutation in ecliptical longitude +8.749" = +0.0024301671° = Nutation in ecliptical obliquity +0.207s = +0.0008627619° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 09.493" = 23.4359701605° Nutation in Obliquity +8.749" = +0.0024301671° True Ecliptic Obliquity 23° 26' 18.241" = 23.4384003276°
Jay Tanner - PHP Science Labs - 2025 - 1.7