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
2460933.5
0.768576388889
-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 Sep 15 [Monday] Gregorian JD Number = 2460934 JD00 = 2460933.5 = JD for 00h of date Local Time = 18:26:45 = 0.768576388889 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) = 2460934.476909722222 Longitude = -76° 49' 23.915" = -76.8233097222° (W) = -05h 07m 17.594s = -5.1215539815 h ================================================================= Local Mean Sidereal Time at Longitude -76.8233097222° (W) 18h 00m 09.125s = 18.0025347459 h 270° 02' 16.88" = 270.0380211892° Local True Sidereal Time at Longitude = -76.8233097222° (W) 18h 00m 09.362s = 18.0026005769 h 270° 02' 20.43" = 270.0390086541° Greenwich Mean Sidereal Time 23h 07m 26.719s = 23.1240887274 h 346° 51' 40.791" = 346.8613309115° Greenwich True Sidereal Time 23h 07m 26.956s = 23.1241545584 h 346° 51' 44.346" = 346.8623183765° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.257069867480 Julian centuries reckoned from J2000.0 t = 0.025706986748 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) +3.875" = +0.0010762711° = Nutation in ecliptical longitude +9.354" = +0.0025984294° = Nutation in ecliptical obliquity +0.237s = +0.0009874650° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 09.415" = 23.4359485453° Nutation in Obliquity +9.354" = +0.0025984294° True Ecliptic Obliquity 23° 26' 18.769" = 23.4385469747°
Jay Tanner - PHP Science Labs - 2025 - 1.7