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
2460795.5
0.237893518519
-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 Apr 30 [Wednesday] Gregorian JD Number = 2460796 JD00 = 2460795.5 = JD for 00h of date Local Time = 05:42:34 = 0.237893518519 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) = 2460795.946226851852 Longitude = -76° 49' 23.915" = -76.8233097222° (W) = -05h 07m 17.594s = -5.1215539815 h ================================================================= Local Mean Sidereal Time at Longitude -76.8233097222° (W) 20h 09m 47.948s = 20.1633189633 h 302° 26' 59.22" = 302.4497844493° Local True Sidereal Time at Longitude = -76.8233097222° (W) 20h 09m 47.962s = 20.1633226532 h 302° 26' 59.42" = 302.4498397981° Greenwich Mean Sidereal Time 01h 17m 05.543s = 1.2848729448 h 19° 16' 23.139" = 19.2730941717° Greenwich True Sidereal Time 01h 17m 05.556s = 1.2848766347 h 19° 16' 23.338" = 19.2731495205° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.253277104089 Julian centuries reckoned from J2000.0 t = 0.025327710408 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) +0.217" = +0.0000603265° = Nutation in ecliptical longitude +9.061" = +0.0025168455° = Nutation in ecliptical obliquity +0.013s = +0.0000553488° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 09.592" = 23.4359978607° Nutation in Obliquity +9.061" = +0.0025168455° True Ecliptic Obliquity 23° 26' 18.653" = 23.4385147062°
Jay Tanner - PHP Science Labs - 2025 - 1.7