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
2461121.5
0.047708333333
-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 Mar 22 [Sunday] Gregorian JD Number = 2461122 JD00 = 2461121.5 = JD for 00h of date Local Time = 01:08:42 = 0.047708333333 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) = 2461121.756041666666 Longitude = -76° 49' 23.915" = -76.8233097222° (W) = -05h 07m 17.594s = -5.1215539815 h ================================================================= Local Mean Sidereal Time at Longitude -76.8233097222° (W) 13h 00m 28.009s = 13.0077803552 h 195° 07' 00.14" = 195.1167053287° Local True Sidereal Time at Longitude = -76.8233097222° (W) 13h 00m 28.383s = 13.0078842392 h 195° 07' 05.75" = 195.1182635882° Greenwich Mean Sidereal Time 18h 07m 45.604s = 18.1293343367 h 271° 56' 24.054" = 271.9400150511° Greenwich True Sidereal Time 18h 07m 45.978s = 18.1294382207 h 271° 56' 29.664" = 271.9415733105° ================================================================= Applied Auxiliary Computations Time Factors Corresponding to Full Astronomical JD T = 0.262197290668 Julian centuries reckoned from J2000.0 t = 0.026219729066 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) +6.114" = +0.0016983971° = Nutation in ecliptical longitude +9.035" = +0.0025096586° = Nutation in ecliptical obliquity +0.374s = +0.0015582595° = Equation of the equinoxes Mean Ecliptic Obliquity 23° 26' 09.175" = 23.4358818760° Nutation in Obliquity +9.035" = +0.0025096586° True Ecliptic Obliquity 23° 26' 18.210" = 23.4383915346°
Jay Tanner - PHP Science Labs - 2026 - 1.7