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
2460781.5
0.569745370370
-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 Apr 16 [Wednesday] Gregorian JD Number = 2460782 JD00 = 2460781.5 = JD for 00h of date Local Time = 13:40:26 = 0.569745370370 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) = 2460782.278078703703 Longitude = -76° 49' 23.915" = -76.8233097222° (W) = -05h 07m 17.594s = -5.1215539815 h ================================================================= Local Mean Sidereal Time at Longitude -76.8233097222° (W) 03h 13m 46.674s = 3.2296317833 h 48° 26' 40.12" = 48.4444767488° Local True Sidereal Time at Longitude = -76.8233097222° (W) 03h 13m 46.679s = 3.2296331206 h 48° 26' 40.19" = 48.4444968088° Greenwich Mean Sidereal Time 08h 21m 04.269s = 8.3511857647 h 125° 16' 04.031" = 125.2677864712° Greenwich True Sidereal Time 08h 21m 04.274s = 8.3511871021 h 125° 16' 04.104" = 125.2678065312° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.252902890587 Julian centuries reckoned from J2000.0 t = 0.025290289058 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) +0.079" = +0.0000218641° = Nutation in ecliptical longitude +9.346" = +0.0025961147° = Nutation in ecliptical obliquity +0.005s = +0.0000200600° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 09.610" = 23.4360027264° Nutation in Obliquity +9.346" = +0.0025961147° True Ecliptic Obliquity 23° 26' 18.956" = 23.4385988411°
Jay Tanner - PHP Science Labs - 2025 - 1.7