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
2460872.5
0.859884259259
-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 16 [Wednesday] Gregorian JD Number = 2460873 JD00 = 2460872.5 = JD for 00h of date Local Time = 20:38:14 = 0.859884259259 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) = 2460873.568217592592 Longitude = -76° 49' 23.915" = -76.8233097222° (W) = -05h 07m 17.594s = -5.1215539815 h ================================================================= Local Mean Sidereal Time at Longitude -76.8233097222° (W) 16h 11m 29.847s = 16.1916241522 h 242° 52' 27.70" = 242.8743622834° Local True Sidereal Time at Longitude = -76.8233097222° (W) 16h 11m 30.055s = 16.1916818867 h 242° 52' 30.82" = 242.8752283009° Greenwich Mean Sidereal Time 21h 18m 47.441s = 21.3131781337 h 319° 41' 51.619" = 319.6976720057° Greenwich True Sidereal Time 21h 18m 47.649s = 21.3132358682 h 319° 41' 54.737" = 319.6985380232° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.255402278373 Julian centuries reckoned from J2000.0 t = 0.025540227837 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) +3.398" = +0.0009439004° = Nutation in ecliptical longitude +8.752" = +0.0024310262° = Nutation in ecliptical obliquity +0.208s = +0.0008660175° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 09.493" = 23.4359702281° Nutation in Obliquity +8.752" = +0.0024310262° True Ecliptic Obliquity 23° 26' 18.245" = 23.4384012544°
Jay Tanner - PHP Science Labs - 2025 - 1.7