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
2460690.5
0.190266203704
-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 = +74 sec = +00h 01m 14s
Double-Click Within Text Area to Select ALL Text
SIDEREAL TIME FOR GIVEN DATE, TIME AND LONGITUDE Local Date = 2025 Jan 15 [Wednesday] Gregorian JD Number = 2460691 JD00 = 2460690.5 = JD for 00h of date Local Time = 04:33:59 = 0.190266203704 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) = 2460690.898599537037 Longitude = -76° 49' 23.915" = -76.8233097222° (W) = -05h 07m 17.594s = -5.1215539815 h ================================================================= Local Mean Sidereal Time at Longitude -76.8233097222° (W) 12h 07m 03.368s = 12.1176022211 h 181° 45' 50.52" = 181.7640333162° Local True Sidereal Time at Longitude = -76.8233097222° (W) 12h 07m 03.440s = 12.1176223250 h 181° 45' 51.61" = 181.7643348743° Greenwich Mean Sidereal Time 17h 14m 20.962s = 17.2391562026 h 258° 35' 14.435" = 258.5873430385° Greenwich True Sidereal Time 17h 14m 21.035s = 17.2391763064 h 258° 35' 15.521" = 258.5876445966° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.250401056797 Julian centuries reckoned from J2000.0 t = 0.025040105679 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) +1.183" = +0.0003286780° = Nutation in ecliptical longitude +8.747" = +0.0024297593° = Nutation in ecliptical obliquity +0.072s = +0.0003015581° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 09.727" = 23.4360352565° Nutation in Obliquity +8.747" = +0.0024297593° True Ecliptic Obliquity 23° 26' 18.474" = 23.4384650158°
Jay Tanner - PHP Science Labs - 2025 - 1.7