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
2461030.5
0.674548611111
-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 Dec 21 [Sunday] Gregorian JD Number = 2461031 JD00 = 2461030.5 = JD for 00h of date Local Time = 16:11:21 = 0.674548611111 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) = 2461031.382881944444 Longitude = -76° 49' 23.915" = -76.8233097222° (W) = -05h 07m 17.594s = -5.1215539815 h ================================================================= Local Mean Sidereal Time at Longitude -76.8233097222° (W) 22h 06m 48.753s = 22.1135425373 h 331° 42' 11.30" = 331.7031380590° Local True Sidereal Time at Longitude = -76.8233097222° (W) 22h 06m 49.066s = 22.1136293354 h 331° 42' 15.98" = 331.7044400303° Greenwich Mean Sidereal Time 03h 14m 06.347s = 3.2350965188 h 48° 31' 35.212" = 48.5264477814° Greenwich True Sidereal Time 03h 14m 06.660s = 3.2351833168 h 48° 31' 39.899" = 48.5277497527° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.259723008403 Julian centuries reckoned from J2000.0 t = 0.025972300840 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) +5.109" = +0.0014190579° = Nutation in ecliptical longitude +8.070" = +0.0022415553° = Nutation in ecliptical obliquity +0.312s = +0.0013019713° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 09.291" = 23.4359140479° Nutation in Obliquity +8.070" = +0.0022415553° True Ecliptic Obliquity 23° 26' 17.360" = 23.4381556031°
Jay Tanner - PHP Science Labs - 2025 - 1.7