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
2460776.5
0.306099537037
-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 11 [Friday] Gregorian JD Number = 2460777 JD00 = 2460776.5 = JD for 00h of date Local Time = 07:20:47 = 0.306099537037 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) = 2460777.01443287037 Longitude = -76° 49' 23.915" = -76.8233097222° (W) = -05h 07m 17.594s = -5.1215539815 h ================================================================= Local Mean Sidereal Time at Longitude -76.8233097222° (W) 20h 33m 22.531s = 20.5562585372 h 308° 20' 37.96" = 308.3438780587° Local True Sidereal Time at Longitude = -76.8233097222° (W) 20h 33m 22.553s = 20.5562647971 h 308° 20' 38.30" = 308.3439719563° Greenwich Mean Sidereal Time 01h 40m 40.125s = 1.6778125187 h 25° 10' 01.876" = 25.1671877811° Greenwich True Sidereal Time 01h 40m 40.148s = 1.6778187786 h 25° 10' 02.214" = 25.1672816786° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.252758779818 Julian centuries reckoned from J2000.0 t = 0.025275877981 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) +0.368" = +0.0001023422° = Nutation in ecliptical longitude +9.617" = +0.0026714211° = Nutation in ecliptical obliquity +0.023s = +0.0000938975° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 09.617" = 23.4360046002° Nutation in Obliquity +9.617" = +0.0026714211° True Ecliptic Obliquity 23° 26' 19.234" = 23.4386760213°
Jay Tanner - PHP Science Labs - 2025 - 1.7