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
2460934.5
0.563657407407
-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 16 [Tuesday] Gregorian JD Number = 2460935 JD00 = 2460934.5 = JD for 00h of date Local Time = 13:31:40 = 0.563657407407 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) = 2460935.27199074074 Longitude = -76° 49' 23.915" = -76.8233097222° (W) = -05h 07m 17.594s = -5.1215539815 h ================================================================= Local Mean Sidereal Time at Longitude -76.8233097222° (W) 13h 08m 12.206s = 13.1367238236 h 197° 03' 03.09" = 197.0508573544° Local True Sidereal Time at Longitude = -76.8233097222° (W) 13h 08m 12.446s = 13.1367906788 h 197° 03' 06.70" = 197.0518601824° Greenwich Mean Sidereal Time 18h 15m 29.800s = 18.2582778051 h 273° 52' 27.001" = 273.8741670768° Greenwich True Sidereal Time 18h 15m 30.041s = 18.2583446603 h 273° 52' 30.612" = 273.8751699048° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.257091635612 Julian centuries reckoned from J2000.0 t = 0.025709163561 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) +3.935" = +0.0010930158° = Nutation in ecliptical longitude +9.385" = +0.0026069313° = Nutation in ecliptical obliquity +0.241s = +0.0010028280° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 09.414" = 23.4359482623° Nutation in Obliquity +9.385" = +0.0026069313° True Ecliptic Obliquity 23° 26' 18.799" = 23.4385551936°
Jay Tanner - PHP Science Labs - 2025 - 1.7