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
0.206076388889
-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 = 04:56:45 = 0.206076388889 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) = 2460873.914409722222 Longitude = -76° 49' 23.915" = -76.8233097222° (W) = -05h 07m 17.594s = -5.1215539815 h ================================================================= Local Mean Sidereal Time at Longitude -76.8233097222° (W) 00h 31m 22.741s = 0.5229834825 h 07° 50' 41.11" = 7.8447522381° Local True Sidereal Time at Longitude = -76.8233097222° (W) 00h 31m 22.947s = 0.5230408369 h 07° 50' 44.20" = 7.8456125529° Greenwich Mean Sidereal Time 05h 38m 40.335s = 5.6445374640 h 84° 40' 05.023" = 84.6680619605° Greenwich True Sidereal Time 05h 38m 40.541s = 5.6445948184 h 84° 40' 08.120" = 84.6689222753° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.255411756597 Julian centuries reckoned from J2000.0 t = 0.025541175659 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) +3.376" = +0.0009376848° = Nutation in ecliptical longitude +8.745" = +0.0024292714° = Nutation in ecliptical obliquity +0.206s = +0.0008603148° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 09.492" = 23.4359701049° Nutation in Obliquity +8.745" = +0.0024292714° True Ecliptic Obliquity 23° 26' 18.238" = 23.4383993763°
Jay Tanner - PHP Science Labs - 2025 - 1.7