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
2460873.5
0.052199074074
-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 Jul 17 [Thursday] Gregorian JD Number = 2460874 JD00 = 2460873.5 = JD for 00h of date Local Time = 01:15:10 = 0.052199074074 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) = 2460873.760532407407 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 49m 11.340s = 20.8198166797 h 312° 17' 50.10" = 312.2972501949° Local True Sidereal Time at Longitude = -76.8233097222° (W) 20h 49m 11.547s = 20.8198741948 h 312° 17' 53.21" = 312.2981129214° Greenwich Mean Sidereal Time 01h 56m 28.934s = 1.9413706612 h 29° 07' 14.016" = 29.1205599173° Greenwich True Sidereal Time 01h 56m 29.141s = 1.9414281762 h 29° 07' 17.122" = 29.1214226437° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.255407543666 Julian centuries reckoned from J2000.0 t = 0.025540754366 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) +3.385" = +0.0009403133° = Nutation in ecliptical longitude +8.749" = +0.0024301559° = Nutation in ecliptical obliquity +0.207s = +0.0008627264° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 09.493" = 23.4359701597° Nutation in Obliquity +8.749" = +0.0024301559° True Ecliptic Obliquity 23° 26' 18.241" = 23.4384003155°
Jay Tanner - PHP Science Labs - 2025 - 1.7