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
0.128587962963
-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 = 03:05:10 = 0.128587962963 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) = 2460873.836921296296 Longitude = -76° 49' 23.915" = -76.8233097222° (W) = -05h 07m 17.594s = -5.1215539815 h ================================================================= Local Mean Sidereal Time at Longitude -76.8233097222° (W) 22h 39m 29.410s = 22.6581695048 h 339° 52' 21.15" = 339.8725425717° Local True Sidereal Time at Longitude = -76.8233097222° (W) 22h 39m 29.617s = 22.6582269383 h 339° 52' 24.25" = 339.8734040744° Greenwich Mean Sidereal Time 03h 46m 47.005s = 3.7797234863 h 56° 41' 45.068" = 56.6958522941° Greenwich True Sidereal Time 03h 46m 47.211s = 3.7797809198 h 56° 41' 48.170" = 56.6967137967° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.255409635079 Julian centuries reckoned from J2000.0 t = 0.025540963507 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) +3.380" = +0.0009389795° = Nutation in ecliptical longitude +8.747" = +0.0024297372° = Nutation in ecliptical obliquity +0.207s = +0.0008615026° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 09.492" = 23.4359701325° Nutation in Obliquity +8.747" = +0.0024297372° True Ecliptic Obliquity 23° 26' 18.240" = 23.4383998697°
Jay Tanner - PHP Science Labs - 2025 - 1.7