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
2460878.5
0.312546296296
-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 22 [Tuesday] Gregorian JD Number = 2460879 JD00 = 2460878.5 = JD for 00h of date Local Time = 07:30:04 = 0.312546296296 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) = 2460879.020879629629 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 24m 49.703s = 3.4138065014 h 51° 12' 25.55" = 51.2070975206° Local True Sidereal Time at Longitude = -76.8233097222° (W) 03h 24m 49.936s = 3.4138711782 h 51° 12' 29.04" = 51.2080676736° Greenwich Mean Sidereal Time 08h 32m 07.298s = 8.5353604829 h 128° 01' 49.466" = 128.0304072429° Greenwich True Sidereal Time 08h 32m 07.531s = 8.5354251597 h 128° 01' 52.959" = 128.0313773960° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.255551564124 Julian centuries reckoned from J2000.0 t = 0.025555156412 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) +3.807" = +0.0010574007° = Nutation in ecliptical longitude +8.591" = +0.0023863058° = Nutation in ecliptical obliquity +0.233s = +0.0009701530° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 09.486" = 23.4359682871° Nutation in Obliquity +8.591" = +0.0023863058° True Ecliptic Obliquity 23° 26' 18.077" = 23.4383545929°
Jay Tanner - PHP Science Labs - 2025 - 1.7