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
2461090.5
0.760277777778
-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 = 2026 Feb 19 [Thursday] Gregorian JD Number = 2461091 JD00 = 2461090.5 = JD for 00h of date Local Time = 18:14:48 = 0.760277777778 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) = 2461091.468611111111 Longitude = -76° 49' 23.915" = -76.8233097222° (W) = -05h 07m 17.594s = -5.1215539815 h ================================================================= Local Mean Sidereal Time at Longitude -76.8233097222° (W) 04h 07m 09.355s = 4.1192652667 h 61° 47' 20.32" = 61.7889789999° Local True Sidereal Time at Longitude = -76.8233097222° (W) 04h 07m 09.785s = 4.1193847657 h 61° 47' 26.78" = 61.7907714856° Greenwich Mean Sidereal Time 09h 14m 26.949s = 9.2408192482 h 138° 36' 44.239" = 138.6122887223° Greenwich True Sidereal Time 09h 14m 27.379s = 9.2409387472 h 138° 36' 50.692" = 138.6140812079° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.261368066012 Julian centuries reckoned from J2000.0 t = 0.026136806601 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) +7.033" = +0.0019536877° = Nutation in ecliptical longitude +8.991" = +0.0024975376° = Nutation in ecliptical obliquity +0.430s = +0.0017924856° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 09.214" = 23.4358926580° Nutation in Obliquity +8.991" = +0.0024975376° True Ecliptic Obliquity 23° 26' 18.205" = 23.4383901956°
Jay Tanner - PHP Science Labs - 2026 - 1.7