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
2460747.5
0.707893518519
-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 Mar 13 [Thursday] Gregorian JD Number = 2460748 JD00 = 2460747.5 = JD for 00h of date Local Time = 16:59:22 = 0.707893518519 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) = 2460748.416226851852 Longitude = -76° 49' 23.915" = -76.8233097222° (W) = -05h 07m 17.594s = -5.1215539815 h ================================================================= Local Mean Sidereal Time at Longitude -76.8233097222° (W) 04h 19m 12.472s = 4.3201309854 h 64° 48' 07.07" = 64.8019647803° Local True Sidereal Time at Longitude = -76.8233097222° (W) 04h 19m 12.549s = 4.3201523661 h 64° 48' 08.23" = 64.8022854919° Greenwich Mean Sidereal Time 09h 26m 30.066s = 9.4416849668 h 141° 37' 30.988" = 141.6252745027° Greenwich True Sidereal Time 09h 26m 30.143s = 9.4417063476 h 141° 37' 32.143" = 141.6255952143° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.251975803609 Julian centuries reckoned from J2000.0 t = 0.025197580360 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) +1.258" = +0.0003495548° = Nutation in ecliptical longitude +9.772" = +0.0027145340° = Nutation in ecliptical obliquity +0.077s = +0.0003207116° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 09.653" = 23.4360147809° Nutation in Obliquity +9.772" = +0.0027145340° True Ecliptic Obliquity 23° 26' 19.426" = 23.4387293149°
Jay Tanner - PHP Science Labs - 2025 - 1.7