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
2460937.5
0.043402777778
-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 Sep 19 [Friday] Gregorian JD Number = 2460938 JD00 = 2460937.5 = JD for 00h of date Local Time = 01:02:30 = 0.043402777778 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) = 2460937.751736111111 Longitude = -76° 49' 23.915" = -76.8233097222° (W) = -05h 07m 17.594s = -5.1215539815 h ================================================================= Local Mean Sidereal Time at Longitude -76.8233097222° (W) 00h 48m 48.803s = 0.8135563455 h 12° 12' 12.04" = 12.2033451819° Local True Sidereal Time at Longitude = -76.8233097222° (W) 00h 48m 49.042s = 0.8136226541 h 12° 12' 15.62" = 12.2043398113° Greenwich Mean Sidereal Time 05h 56m 06.397s = 5.9351103269 h 89° 01' 35.958" = 89.0266549042° Greenwich True Sidereal Time 05h 56m 06.636s = 5.9351766356 h 89° 01' 39.538" = 89.0276495336° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.257159527340 Julian centuries reckoned from J2000.0 t = 0.025715952734 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) +3.903" = +0.0010840802° = Nutation in ecliptical longitude +9.516" = +0.0026434718° = Nutation in ecliptical obliquity +0.239s = +0.0009946294° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 09.411" = 23.4359473795° Nutation in Obliquity +9.516" = +0.0026434718° True Ecliptic Obliquity 23° 26' 18.927" = 23.4385908514°
Jay Tanner - PHP Science Labs - 2025 - 1.7