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
2461023.5
0.748900462963
-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 Dec 14 [Sunday] Gregorian JD Number = 2461024 JD00 = 2461023.5 = JD for 00h of date Local Time = 17:58:25 = 0.748900462963 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) = 2461024.457233796296 Longitude = -76° 49' 23.915" = -76.8233097222° (W) = -05h 07m 17.594s = -5.1215539815 h ================================================================= Local Mean Sidereal Time at Longitude -76.8233097222° (W) 23h 26m 34.454s = 23.4429038548 h 351° 38' 36.81" = 351.6435578219° Local True Sidereal Time at Longitude = -76.8233097222° (W) 23h 26m 34.723s = 23.4429786163 h 351° 38' 40.84" = 351.6446792445° Greenwich Mean Sidereal Time 04h 33m 52.048s = 4.5644578363 h 68° 28' 00.723" = 68.4668675442° Greenwich True Sidereal Time 04h 33m 52.317s = 4.5645325978 h 68° 28' 04.760" = 68.4679889669° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.259533394491 Julian centuries reckoned from J2000.0 t = 0.025953339449 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) +4.400" = +0.0012222729° = Nutation in ecliptical longitude +8.239" = +0.0022885034° = Nutation in ecliptical obliquity +0.269s = +0.0011214226° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 09.299" = 23.4359165133° Nutation in Obliquity +8.239" = +0.0022885034° True Ecliptic Obliquity 23° 26' 17.538" = 23.4382050168°
Jay Tanner - PHP Science Labs - 2025 - 1.7