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
2460964.5
0.582187500000
-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 Oct 16 [Thursday] Gregorian JD Number = 2460965 JD00 = 2460964.5 = JD for 00h of date Local Time = 13:58:21 = 0.582187500000 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) = 2460965.290520833333 Longitude = -76° 49' 23.915" = -76.8233097222° (W) = -05h 07m 17.594s = -5.1215539815 h ================================================================= Local Mean Sidereal Time at Longitude -76.8233097222° (W) 15h 33m 14.250s = 15.5539584003 h 233° 18' 33.75" = 233.3093760046° Local True Sidereal Time at Longitude = -76.8233097222° (W) 15h 33m 14.446s = 15.5540127345 h 233° 18' 36.69" = 233.3101910181° Greenwich Mean Sidereal Time 20h 40m 31.845s = 20.6755123818 h 310° 07' 57.669" = 310.1326857270° Greenwich True Sidereal Time 20h 40m 32.040s = 20.6755667160 h 310° 08' 00.603" = 310.1335007405° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.257913498174 Julian centuries reckoned from J2000.0 t = 0.025791349817 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) +3.198" = +0.0008883103° = Nutation in ecliptical longitude +9.305" = +0.0025847941° = Nutation in ecliptical obliquity +0.196s = +0.0008150135° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 09.375" = 23.4359375760° Nutation in Obliquity +9.305" = +0.0025847941° True Ecliptic Obliquity 23° 26' 18.681" = 23.4385223701°
Jay Tanner - PHP Science Labs - 2025 - 1.7