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
2461032.5
0.901122685185
-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 23 [Tuesday] Gregorian JD Number = 2461033 JD00 = 2461032.5 = JD for 00h of date Local Time = 21:37:37 = 0.901122685185 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) = 2461033.609456018518 Longitude = -76° 49' 23.915" = -76.8233097222° (W) = -05h 07m 17.594s = -5.1215539815 h ================================================================= Local Mean Sidereal Time at Longitude -76.8233097222° (W) 03h 41m 51.461s = 3.6976281058 h 55° 27' 51.92" = 55.4644215871° Local True Sidereal Time at Longitude = -76.8233097222° (W) 03h 41m 51.786s = 3.6977183012 h 55° 27' 56.79" = 55.4657745183° Greenwich Mean Sidereal Time 08h 49m 09.056s = 8.8191820873 h 132° 17' 15.833" = 132.2877313094° Greenwich True Sidereal Time 08h 49m 09.380s = 8.8192722827 h 132° 17' 20.703" = 132.2890842407° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.259783968679 Julian centuries reckoned from J2000.0 t = 0.025978396867 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) +5.309" = +0.0014746009° = Nutation in ecliptical longitude +8.167" = +0.0022684766° = Nutation in ecliptical obliquity +0.325s = +0.0013529312° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 09.288" = 23.4359132552° Nutation in Obliquity +8.167" = +0.0022684766° True Ecliptic Obliquity 23° 26' 17.454" = 23.4381817318°
Jay Tanner - PHP Science Labs - 2025 - 1.7