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
2460874.5
0.972685185185
-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 18 [Friday] Gregorian JD Number = 2460875 JD00 = 2460874.5 = JD for 00h of date Local Time = 23:20:40 = 0.972685185185 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) = 2460875.681018518518 Longitude = -76° 49' 23.915" = -76.8233097222° (W) = -05h 07m 17.594s = -5.1215539815 h ================================================================= Local Mean Sidereal Time at Longitude -76.8233097222° (W) 19h 02m 15.641s = 19.0376781542 h 285° 33' 54.62" = 285.5651723123° Local True Sidereal Time at Longitude = -76.8233097222° (W) 19h 02m 15.846s = 19.0377351096 h 285° 33' 57.70" = 285.5660266443° Greenwich Mean Sidereal Time 00h 09m 33.236s = 0.1592321356 h 02° 23' 18.535" = 2.3884820347° Greenwich True Sidereal Time 00h 09m 33.441s = 0.1592890911 h 02° 23' 21.611" = 2.3893363666° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.255460123710 Julian centuries reckoned from J2000.0 t = 0.025546012371 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) +3.352" = +0.0009311638° = Nutation in ecliptical longitude +8.677" = +0.0024102807° = Nutation in ecliptical obliquity +0.205s = +0.0008543319° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 09.490" = 23.4359694760° Nutation in Obliquity +8.677" = +0.0024102807° True Ecliptic Obliquity 23° 26' 18.167" = 23.4383797567°
Jay Tanner - PHP Science Labs - 2025 - 1.7