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
2461301.5
0.040312500000
-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 18 [Friday] Gregorian JD Number = 2461302 JD00 = 2461301.5 = JD for 00h of date Local Time = 00:58:03 = 0.040312500000 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) = 2461301.748645833333 Longitude = -76° 49' 23.915" = -76.8233097222° (W) = -05h 07m 17.594s = -5.1215539815 h ================================================================= Local Mean Sidereal Time at Longitude -76.8233097222° (W) 00h 39m 27.226s = 0.6575628409 h 09° 51' 48.39" = 9.8634426137° Local True Sidereal Time at Longitude = -76.8233097222° (W) 00h 39m 27.766s = 0.6577128424 h 09° 51' 56.49" = 9.8656926357° Greenwich Mean Sidereal Time 05h 46m 44.821s = 5.7791168224 h 86° 41' 12.308" = 86.6867523361° Greenwich True Sidereal Time 05h 46m 45.361s = 5.7792668239 h 86° 41' 20.408" = 86.6890023580° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.267125219598 Julian centuries reckoned from J2000.0 t = 0.026712521959 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) +8.829" = +0.0024523660° = Nutation in ecliptical longitude +8.252" = +0.0022923170° = Nutation in ecliptical obliquity +0.540s = +0.0022500219° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 08.944" = 23.4358178007° Nutation in Obliquity +8.252" = +0.0022923170° True Ecliptic Obliquity 23° 26' 17.196" = 23.4381101177°
Jay Tanner - PHP Science Labs - 2026 - 1.7