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
2460854.5
0.135949074074
-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 Jun 28 [Saturday] Gregorian JD Number = 2460855 JD00 = 2460854.5 = JD for 00h of date Local Time = 03:15:46 = 0.135949074074 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) = 2460854.844282407407 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 35m 12.600s = 21.5868332008 h 323° 48' 08.99" = 323.8024980123° Local True Sidereal Time at Longitude = -76.8233097222° (W) 21h 35m 12.783s = 21.5868842062 h 323° 48' 11.75" = 323.8032630925° Greenwich Mean Sidereal Time 02h 42m 30.194s = 2.7083871823 h 40° 37' 32.908" = 40.6258077347° Greenwich True Sidereal Time 02h 42m 30.377s = 2.7084381877 h 40° 37' 35.662" = 40.6265728148° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.254889644966 Julian centuries reckoned from J2000.0 t = 0.025488964496 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) +3.002" = +0.0008338851° = Nutation in ecliptical longitude +8.481" = +0.0023558230° = Nutation in ecliptical obliquity +0.184s = +0.0007650801° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 09.517" = 23.4359768937° Nutation in Obliquity +8.481" = +0.0023558230° True Ecliptic Obliquity 23° 26' 17.998" = 23.4383327166°
Jay Tanner - PHP Science Labs - 2025 - 1.7