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
2460935.5
0.913993055556
-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 17 [Wednesday] Gregorian JD Number = 2460936 JD00 = 2460935.5 = JD for 00h of date Local Time = 21:56:09 = 0.913993055556 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) = 2460936.622326388889 Longitude = -76° 49' 23.915" = -76.8233097222° (W) = -05h 07m 17.594s = -5.1215539815 h ================================================================= Local Mean Sidereal Time at Longitude -76.8233097222° (W) 21h 38m 00.635s = 21.6335097013 h 324° 30' 09.52" = 324.5026455191° Local True Sidereal Time at Longitude = -76.8233097222° (W) 21h 38m 00.877s = 21.6335770102 h 324° 30' 13.16" = 324.5036551535° Greenwich Mean Sidereal Time 02h 45m 18.229s = 2.7550636828 h 41° 19' 33.439" = 41.3259552415° Greenwich True Sidereal Time 02h 45m 18.472s = 2.7551309917 h 41° 19' 37.074" = 41.3269648758° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.257128605787 Julian centuries reckoned from J2000.0 t = 0.025712860578 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) +3.962" = +0.0011004345° = Nutation in ecliptical longitude +9.456" = +0.0026266619° = Nutation in ecliptical obliquity +0.242s = +0.0010096344° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 09.412" = 23.4359477816° Nutation in Obliquity +9.456" = +0.0026266619° True Ecliptic Obliquity 23° 26' 18.868" = 23.4385744435°
Jay Tanner - PHP Science Labs - 2025 - 1.7