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
2460746.5
0.815069444444
-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 Mar 12 [Wednesday] Gregorian JD Number = 2460747 JD00 = 2460746.5 = JD for 00h of date Local Time = 19:33:42 = 0.815069444444 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) = 2460747.523402777777 Longitude = -76° 49' 23.915" = -76.8233097222° (W) = -05h 07m 17.594s = -5.1215539815 h ================================================================= Local Mean Sidereal Time at Longitude -76.8233097222° (W) 06h 50m 01.269s = 6.8336859010 h 102° 30' 19.04" = 102.5052885148° Local True Sidereal Time at Longitude = -76.8233097222° (W) 06h 50m 01.353s = 6.8337093028 h 102° 30' 20.30" = 102.5056395418° Greenwich Mean Sidereal Time 11h 57m 18.864s = 11.9552398825 h 179° 19' 42.954" = 179.3285982371° Greenwich True Sidereal Time 11h 57m 18.948s = 11.9552632843 h 179° 19' 44.217" = 179.3289492641° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.251951359418 Julian centuries reckoned from J2000.0 t = 0.025195135941 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) +1.377" = +0.0003825966° = Nutation in ecliptical longitude +9.746" = +0.0027071520° = Nutation in ecliptical obliquity +0.084s = +0.0003510270° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 09.654" = 23.4360150987° Nutation in Obliquity +9.746" = +0.0027071520° True Ecliptic Obliquity 23° 26' 19.400" = 23.4387222507°
Jay Tanner - PHP Science Labs - 2025 - 1.7