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
2461160.5
0.163807870370
-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 Apr 30 [Thursday] Gregorian JD Number = 2461161 JD00 = 2461160.5 = JD for 00h of date Local Time = 03:55:53 = 0.163807870370 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) = 2461160.872141203703 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 21m 52.133s = 18.3644812988 h 275° 28' 01.99" = 275.4672194817° Local True Sidereal Time at Longitude = -76.8233097222° (W) 18h 21m 52.475s = 18.3645764766 h 275° 28' 07.13" = 275.4686471494° Greenwich Mean Sidereal Time 23h 29m 09.727s = 23.4860352803 h 352° 17' 25.905" = 352.2905292041° Greenwich True Sidereal Time 23h 29m 10.070s = 23.4861304581 h 352° 17' 31.045" = 352.2919568718° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.263268231107 Julian centuries reckoned from J2000.0 t = 0.026326823110 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) +5.602" = +0.0015560591° = Nutation in ecliptical longitude +8.511" = +0.0023641254° = Nutation in ecliptical obliquity +0.343s = +0.0014276677° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 09.125" = 23.4358679511° Nutation in Obliquity +8.511" = +0.0023641254° True Ecliptic Obliquity 23° 26' 17.635" = 23.4382320765°
Jay Tanner - PHP Science Labs - 2026 - 1.7