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
2461288.5
0.997430555556
-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 = +76 sec = +00h 01m 16s
Double-Click Within Text Area to Select ALL Text
SIDEREAL TIME FOR GIVEN DATE, TIME AND LONGITUDE Local Date = 2026 Sep 05 [Saturday] Gregorian JD Number = 2461289 JD00 = 2461288.5 = JD for 00h of date Local Time = 23:56:18 = 0.997430555556 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) = 2461289.705763888889 Longitude = -76° 49' 23.915" = -76.8233097222° (W) = -05h 07m 17.594s = -5.1215539815 h ================================================================= Local Mean Sidereal Time at Longitude -76.8233097222° (W) 22h 50m 13.418s = 22.8370605171 h 342° 33' 21.27" = 342.5559077570° Local True Sidereal Time at Longitude = -76.8233097222° (W) 22h 50m 13.989s = 22.8372191505 h 342° 33' 29.83" = 342.5582872571° Greenwich Mean Sidereal Time 03h 57m 31.012s = 3.9586144986 h 59° 22' 45.183" = 59.3792174794° Greenwich True Sidereal Time 03h 57m 31.583s = 3.9587731320 h 59° 22' 53.749" = 59.3815969794° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.266795503460 Julian centuries reckoned from J2000.0 t = 0.026679550346 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) +9.337" = +0.0025934879° = Nutation in ecliptical longitude +8.207" = +0.0022796154° = Nutation in ecliptical obliquity +0.571s = +0.0023795001° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 08.960" = 23.4358220878° Nutation in Obliquity +8.207" = +0.0022796154° True Ecliptic Obliquity 23° 26' 17.166" = 23.4381017033°
Jay Tanner - PHP Science Labs - 2026 - 1.7