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
2460933.5
0.430543981481
-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 Sep 15 [Monday] Gregorian JD Number = 2460934 JD00 = 2460933.5 = JD for 00h of date Local Time = 10:19:59 = 0.430543981481 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) = 2460934.138877314814 Longitude = -76° 49' 23.915" = -76.8233097222° (W) = -05h 07m 17.594s = -5.1215539815 h ================================================================= Local Mean Sidereal Time at Longitude -76.8233097222° (W) 09h 52m 03.162s = 9.8675449224 h 148° 00' 47.43" = 148.0131738358° Local True Sidereal Time at Longitude = -76.8233097222° (W) 09h 52m 03.397s = 9.8676101913 h 148° 00' 50.95" = 148.0141528691° Greenwich Mean Sidereal Time 14h 59m 20.756s = 14.9890989039 h 224° 50' 11.341" = 224.8364835582° Greenwich True Sidereal Time 14h 59m 20.991s = 14.9891641728 h 224° 50' 14.865" = 224.8374625914° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.257060612657 Julian centuries reckoned from J2000.0 t = 0.025706061265 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) +3.841" = +0.0010670811° = Nutation in ecliptical longitude +9.345" = +0.0025959588° = Nutation in ecliptical obliquity +0.235s = +0.0009790333° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 09.415" = 23.4359486657° Nutation in Obliquity +9.345" = +0.0025959588° True Ecliptic Obliquity 23° 26' 18.761" = 23.4385446245°
Jay Tanner - PHP Science Labs - 2025 - 1.7