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
2460818.5
0.909259259259
-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 May 23 [Friday] Gregorian JD Number = 2460819 JD00 = 2460818.5 = JD for 00h of date Local Time = 21:49:20 = 0.909259259259 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) = 2460819.617592592592 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 49m 53.537s = 13.8315380354 h 207° 28' 23.05" = 207.4730705307° Local True Sidereal Time at Longitude = -76.8233097222° (W) 13h 49m 53.574s = 13.8315482491 h 207° 28' 23.61" = 207.4732237369° Greenwich Mean Sidereal Time 18h 57m 11.131s = 18.9530920169 h 284° 17' 46.969" = 284.2963802530° Greenwich True Sidereal Time 18h 57m 11.168s = 18.9531022306 h 284° 17' 47.520" = 284.2965334593° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.253925190762 Julian centuries reckoned from J2000.0 t = 0.025392519076 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) +0.601" = +0.0001669845° = Nutation in ecliptical longitude +8.825" = +0.0024513568° = Nutation in ecliptical obliquity +0.037s = +0.0001532063° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 09.562" = 23.4359894340° Nutation in Obliquity +8.825" = +0.0024513568° True Ecliptic Obliquity 23° 26' 18.387" = 23.4384407907°
Jay Tanner - PHP Science Labs - 2025 - 1.7