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
2461174.5
0.118506944444
-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 14 [Thursday] Gregorian JD Number = 2461175 JD00 = 2461174.5 = JD for 00h of date Local Time = 02:50:39 = 0.118506944444 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) = 2461174.826840277777 Longitude = -76° 49' 23.915" = -76.8233097222° (W) = -05h 07m 17.594s = -5.1215539815 h ================================================================= Local Mean Sidereal Time at Longitude -76.8233097222° (W) 18h 11m 39.192s = 18.1942199040 h 272° 54' 47.88" = 272.9132985598° Local True Sidereal Time at Longitude = -76.8233097222° (W) 18h 11m 39.540s = 18.1943166467 h 272° 54' 53.10" = 272.9147496999° Greenwich Mean Sidereal Time 23h 18m 56.786s = 23.3157738855 h 349° 44' 11.790" = 349.7366082822° Greenwich True Sidereal Time 23h 18m 57.134s = 23.3158706282 h 349° 44' 17.014" = 349.7380594223° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.263650289946 Julian centuries reckoned from J2000.0 t = 0.026365028994 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) +5.694" = +0.0015816413° = Nutation in ecliptical longitude +8.225" = +0.0022845910° = Nutation in ecliptical obliquity +0.348s = +0.0014511401° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 09.107" = 23.4358629834° Nutation in Obliquity +8.225" = +0.0022845910° True Ecliptic Obliquity 23° 26' 17.331" = 23.4381475744°
Jay Tanner - PHP Science Labs - 2026 - 1.7