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
2460804.5
0.174201388889
-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 May 09 [Friday] Gregorian JD Number = 2460805 JD00 = 2460804.5 = JD for 00h of date Local Time = 04:10:51 = 0.174201388889 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) = 2460804.882534722222 Longitude = -76° 49' 23.915" = -76.8233097222° (W) = -05h 07m 17.594s = -5.1215539815 h ================================================================= Local Mean Sidereal Time at Longitude -76.8233097222° (W) 19h 13m 18.880s = 19.2219110752 h 288° 19' 43.20" = 288.3286661282° Local True Sidereal Time at Longitude = -76.8233097222° (W) 19h 13m 18.900s = 19.2219167417 h 288° 19' 43.50" = 288.3287511254° Greenwich Mean Sidereal Time 00h 20m 36.474s = 0.3434650567 h 05° 09' 07.113" = 5.1519758506° Greenwich True Sidereal Time 00h 20m 36.495s = 0.3434707232 h 05° 09' 07.419" = 5.1520608477° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.253521766864 Julian centuries reckoned from J2000.0 t = 0.025352176686 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) +0.334" = +0.0000926412° = Nutation in ecliptical longitude +9.100" = +0.0025278280° = Nutation in ecliptical obliquity +0.020s = +0.0000849972° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 09.581" = 23.4359946795° Nutation in Obliquity +9.100" = +0.0025278280° True Ecliptic Obliquity 23° 26' 18.681" = 23.4385225075°
Jay Tanner - PHP Science Labs - 2025 - 1.7