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
2460857.5
0.216643518519
-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 01 [Tuesday] Gregorian JD Number = 2460858 JD00 = 2460857.5 = JD for 00h of date Local Time = 05:11:58 = 0.216643518519 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) = 2460857.924976851852 Longitude = -76° 49' 23.915" = -76.8233097222° (W) = -05h 07m 17.594s = -5.1215539815 h ================================================================= Local Mean Sidereal Time at Longitude -76.8233097222° (W) 23h 43m 33.354s = 23.7259317604 h 355° 53' 20.32" = 355.8889764063° Local True Sidereal Time at Longitude = -76.8233097222° (W) 23h 43m 33.534s = 23.7259816853 h 355° 53' 23.01" = 355.8897252799° Greenwich Mean Sidereal Time 04h 50m 50.949s = 4.8474857419 h 72° 42' 44.230" = 72.7122861287° Greenwich True Sidereal Time 04h 50m 51.128s = 4.8475356668 h 72° 42' 46.926" = 72.7130350023° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.254973989783 Julian centuries reckoned from J2000.0 t = 0.025497398978 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) +2.938" = +0.0008162213° = Nutation in ecliptical longitude +8.608" = +0.0023909976° = Nutation in ecliptical obliquity +0.180s = +0.0007488736° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 09.513" = 23.4359757970° Nutation in Obliquity +8.608" = +0.0023909976° True Ecliptic Obliquity 23° 26' 18.120" = 23.4383667945°
Jay Tanner - PHP Science Labs - 2025 - 1.7