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
2460873.5
0.281736111111
-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 17 [Thursday] Gregorian JD Number = 2460874 JD00 = 2460873.5 = JD for 00h of date Local Time = 06:45:42 = 0.281736111111 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) = 2460873.990069444444 Longitude = -76° 49' 23.915" = -76.8233097222° (W) = -05h 07m 17.594s = -5.1215539815 h ================================================================= Local Mean Sidereal Time at Longitude -76.8233097222° (W) 02h 20m 37.638s = 2.3437883998 h 35° 09' 24.57" = 35.1568259965° Local True Sidereal Time at Longitude = -76.8233097222° (W) 02h 20m 37.844s = 2.3438456804 h 35° 09' 27.67" = 35.1576852067° Greenwich Mean Sidereal Time 07h 27m 55.233s = 7.4653423813 h 111° 58' 48.489" = 111.9801357188° Greenwich True Sidereal Time 07h 27m 55.439s = 7.4653996619 h 111° 58' 51.582" = 111.9809949291° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.255413828047 Julian centuries reckoned from J2000.0 t = 0.025541382804 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) +3.371" = +0.0009364809° = Nutation in ecliptical longitude +8.744" = +0.0024287776° = Nutation in ecliptical obliquity +0.206s = +0.0008592102° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 09.492" = 23.4359700780° Nutation in Obliquity +8.744" = +0.0024287776° True Ecliptic Obliquity 23° 26' 18.236" = 23.4383988556°
Jay Tanner - PHP Science Labs - 2025 - 1.7