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
2460874.5
0.952291666667
-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 18 [Friday] Gregorian JD Number = 2460875 JD00 = 2460874.5 = JD for 00h of date Local Time = 22:51:18 = 0.952291666667 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) = 2460875.660625 Longitude = -76° 49' 23.915" = -76.8233097222° (W) = -05h 07m 17.594s = -5.1215539815 h ================================================================= Local Mean Sidereal Time at Longitude -76.8233097222° (W) 18h 32m 48.817s = 18.5468936501 h 278° 12' 12.26" = 278.2034047511° Local True Sidereal Time at Longitude = -76.8233097222° (W) 18h 32m 49.022s = 18.5469505914 h 278° 12' 15.33" = 278.2042588707° Greenwich Mean Sidereal Time 23h 40m 06.411s = 23.6684476316 h 355° 01' 36.172" = 355.0267144735° Greenwich True Sidereal Time 23h 40m 06.616s = 23.6685045729 h 355° 01' 39.247" = 355.0275685931° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.255459565366 Julian centuries reckoned from J2000.0 t = 0.025545956536 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) +3.351" = +0.0009309323° = Nutation in ecliptical longitude +8.678" = +0.0024105542° = Nutation in ecliptical obliquity +0.205s = +0.0008541196° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 09.490" = 23.4359694833° Nutation in Obliquity +8.678" = +0.0024105542° True Ecliptic Obliquity 23° 26' 18.168" = 23.4383800375°
Jay Tanner - PHP Science Labs - 2025 - 1.7