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
2460817.5
0.414942129630
-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 May 22 [Thursday] Gregorian JD Number = 2460818 JD00 = 2460817.5 = JD for 00h of date Local Time = 09:57:31 = 0.414942129630 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) = 2460818.123275462963 Longitude = -76° 49' 23.915" = -76.8233097222° (W) = -05h 07m 17.594s = -5.1215539815 h ================================================================= Local Mean Sidereal Time at Longitude -76.8233097222° (W) 01h 52m 11.048s = 1.8697356053 h 28° 02' 45.72" = 28.0460340800° Local True Sidereal Time at Longitude = -76.8233097222° (W) 01h 52m 11.092s = 1.8697477122 h 28° 02' 46.38" = 28.0462156826° Greenwich Mean Sidereal Time 06h 59m 28.643s = 6.9912895868 h 104° 52' 09.638" = 104.8693438023° Greenwich True Sidereal Time 06h 59m 28.686s = 6.9913016937 h 104° 52' 10.291" = 104.8695254050° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.253884278588 Julian centuries reckoned from J2000.0 t = 0.025388427858 Julian millennia reckoned from J2000.0 Nutations (IAU 2000B Series) +0.713" = +0.0001979347° = Nutation in ecliptical longitude +8.883" = +0.0024674909° = Nutation in ecliptical obliquity +0.044s = +0.0001816027° = Equation of the equinoxes Mean Obliquity of the Ecliptic 23° 26' 09.564" = 23.4359899659° True Obliquity of the Ecliptic 23° 26' 18.447" = 23.4384574569°
Jay Tanner - PHP Science Labs - 2025 - 1.7