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
2460857.5
0.114479166667
-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 01 [Tuesday] Gregorian JD Number = 2460858 JD00 = 2460857.5 = JD for 00h of date Local Time = 02:44:51 = 0.114479166667 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) = 2460857.8228125 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 16m 02.187s = 21.2672741144 h 319° 00' 32.80" = 319.0091117164° Local True Sidereal Time at Longitude = -76.8233097222° (W) 21h 16m 02.367s = 21.2673241534 h 319° 00' 35.50" = 319.0098623009° Greenwich Mean Sidereal Time 02h 23m 19.781s = 2.3888280959 h 35° 49' 56.717" = 35.8324214388° Greenwich True Sidereal Time 02h 23m 19.961s = 2.3888781349 h 35° 49' 59.419" = 35.8331720233° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.254971192676 Julian centuries reckoned from J2000.0 t = 0.025497119267 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) +2.945" = +0.0008180860° = Nutation in ecliptical longitude +8.606" = +0.0023905823° = Nutation in ecliptical obliquity +0.180s = +0.0007505845° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 09.513" = 23.4359758333° Nutation in Obliquity +8.606" = +0.0023905823° True Ecliptic Obliquity 23° 26' 18.119" = 23.4383664156°
Jay Tanner - PHP Science Labs - 2025 - 1.7