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
2460931.5
0.308472222222
-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 13 [Saturday] Gregorian JD Number = 2460932 JD00 = 2460931.5 = JD for 00h of date Local Time = 07:24:12 = 0.308472222222 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) = 2460932.016805555555 Longitude = -76° 49' 23.915" = -76.8233097222° (W) = -05h 07m 17.594s = -5.1215539815 h ================================================================= Local Mean Sidereal Time at Longitude -76.8233097222° (W) 06h 47m 54.174s = 6.7983817355 h 101° 58' 32.61" = 101.9757260322° Local True Sidereal Time at Longitude = -76.8233097222° (W) 06h 47m 54.395s = 6.7984430611 h 101° 58' 35.92" = 101.9766459169° Greenwich Mean Sidereal Time 11h 55m 11.769s = 11.9199357170 h 178° 47' 56.529" = 178.7990357545° Greenwich True Sidereal Time 11h 55m 11.989s = 11.9199970426 h 178° 47' 59.840" = 178.7999556392° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.257002513499 Julian centuries reckoned from J2000.0 t = 0.025700251349 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) +3.609" = +0.0010026131° = Nutation in ecliptical longitude +9.360" = +0.0026001037° = Nutation in ecliptical obliquity +0.221s = +0.0009198847° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 09.418" = 23.4359494211° Nutation in Obliquity +9.360" = +0.0026001037° True Ecliptic Obliquity 23° 26' 18.778" = 23.4385495248°
Jay Tanner - PHP Science Labs - 2025 - 1.7