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
2461181.5
0.771793981481
-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 = 2026 May 21 [Thursday] Gregorian JD Number = 2461182 JD00 = 2461181.5 = JD for 00h of date Local Time = 18:31:23 = 0.771793981481 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) = 2461182.480127314814 Longitude = -76° 49' 23.915" = -76.8233097222° (W) = -05h 07m 17.594s = -5.1215539815 h ================================================================= Local Mean Sidereal Time at Longitude -76.8233097222° (W) 10h 22m 33.618s = 10.3760049489 h 155° 38' 24.27" = 155.6400742340° Local True Sidereal Time at Longitude = -76.8233097222° (W) 10h 22m 34.019s = 10.3761162822 h 155° 38' 30.28" = 155.6417442325° Greenwich Mean Sidereal Time 15h 29m 51.212s = 15.4975589304 h 232° 27' 48.182" = 232.4633839563° Greenwich True Sidereal Time 15h 29m 51.613s = 15.4976702637 h 232° 27' 54.194" = 232.4650539548° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.263859825525 Julian centuries reckoned from J2000.0 t = 0.026385982552 Julian millennia reckoned from J2000.0 Nutations (IAU 2000B Series) +6.553" = +0.0018201806° = Nutation in ecliptical longitude +7.962" = +0.0022117070° = Nutation in ecliptical obliquity +0.401s = +0.0016699985° = Equation of the equinoxes Mean Obliquity of the Ecliptic 23° 26' 09.097" = 23.4358602589° True Obliquity of the Ecliptic 23° 26' 17.059" = 23.4380719660°
Jay Tanner - PHP Science Labs - 2026 - 1.7