Julian Date and Julian Day Number Calculator Valid Over The Period From 1600 to 2200 on the Gregorian Calendar
Local Calendar Date   Year      Month    Day	Local Clock Time 00:00  to  24:00	Local Time Zone Offset From UT Negative | Positive  =  West | East UTC
Julian Date ============================================================================= Calendar Date Time Julian Date JD Num =============== ============ ================ ======= Local Date/Time LT 2025-Jul-17-Thu 08:33:23 LT 2460873.85651620 2460874 Local Time Zone TZ +00:00:00 TZ +0.00000000 Universal Time UTC 2025-Jul-17-Thu 08:33:23 UTC 2460873.85651620 2460874 Delta T Correction +00:01:09 DT +0.00080074 Terrestrial Time TT 2025-Jul-17-Thu 08:34:32 TT 2460873.85731694 2460874 TAI Correction -00:00:32.184 -0.00037250 Atomic Time TAI 2025-Jul-17-Thu 08:34:00 TAI 2460873.85694444 2460874 Astronomical JD TT 2460873.85731694 Horizons Delta T +69.183676 sec ============================================================================= ======================================== JD NUMBER TABLE Year:2025 | Month:Jul Gregorian Calendar Calendar Date JD Number Julian Date Year-Mmm-Dn-DoW JD at 12h JD at 00h ---------------- --------- ----------- 2025-Jul-01-Tue 2460858 2460857.5 2025-Jul-02-Wed 2460859 2460858.5 2025-Jul-03-Thu 2460860 2460859.5 2025-Jul-04-Fri 2460861 2460860.5 2025-Jul-05-Sat 2460862 2460861.5 2025-Jul-06-Sun 2460863 2460862.5 2025-Jul-07-Mon 2460864 2460863.5 2025-Jul-08-Tue 2460865 2460864.5 2025-Jul-09-Wed 2460866 2460865.5 2025-Jul-10-Thu 2460867 2460866.5 2025-Jul-11-Fri 2460868 2460867.5 2025-Jul-12-Sat 2460869 2460868.5 2025-Jul-13-Sun 2460870 2460869.5 2025-Jul-14-Mon 2460871 2460870.5 2025-Jul-15-Tue 2460872 2460871.5 2025-Jul-16-Wed 2460873 2460872.5 2025-Jul-17-Thu 2460874 2460873.5 2025-Jul-18-Fri 2460875 2460874.5 2025-Jul-19-Sat 2460876 2460875.5 2025-Jul-20-Sun 2460877 2460876.5 2025-Jul-21-Mon 2460878 2460877.5 2025-Jul-22-Tue 2460879 2460878.5 2025-Jul-23-Wed 2460880 2460879.5 2025-Jul-24-Thu 2460881 2460880.5 2025-Jul-25-Fri 2460882 2460881.5 2025-Jul-26-Sat 2460883 2460882.5 2025-Jul-27-Sun 2460884 2460883.5 2025-Jul-28-Mon 2460885 2460884.5 2025-Jul-29-Tue 2460886 2460885.5 2025-Jul-30-Wed 2460887 2460886.5 2025-Jul-31-Thu 2460888 2460887.5 ---------------- --------- ----------- Year-Mmm-Dn-DoW JD Number Julian Date Calendar Date JD at 12h JD at 00h ========================================
SYMBOLS, TIME SCALES AND RELATIONSHIPS LT = Local (Clock) Time TZ = Local Standard Time Zone Offset From UT (Negative|Positive = West|East) NOTE: When Daylight Saving or Summer Time is in effect, then the time zone offset is one hour less than under standard time. For example, the standard time zone offset for New York City, USA, is −5 hours when standard time is in effect but when Daylight Saving Time is in effect, the time zone offset from UT is −4 hours instead. Universal Time is always standard time. UT = Universal Time Scale = UT1 From 1600 to 1961 = UTC From 1962 onward = LT − (TZ) DT = Horizons Delta T (Could be negative or positive, depending on date.) = TT − UT TT = Terrestrial Time Scale (Used for formal astronomical computations.) = UT + (DT) = LT − (TZ) + (DT) TAI = International Atomic Time Scale = TT − 00:00:32.184 = LT - (TZ) + (DT) − 00:00:32.184 JD = Julian Date (a floating point decimal value). Contains both the complete calendar date and time of day information where the decimal fraction part indicates the time of day. JD Number = Julian Day Number (always an integer value). = Unique sequential serial number of the date on the calendar. It contains only the calendar date information. = floor(JD + 0.5) DoW = Day of Week index (0=Sun, 1=Mon, 2=Tue, 3=Wed, 4=Thu, 5=Fri, 6=Sat) = (floor(JD + 0.5) + 1) mod 7 = (JDNumber + 1) mod 7
Download This PHP 7 Program: 598 kb - Julian Date and JD Number Calculator
Program by Jay Tanner Revised: Thursday, January 01, 1970 at 12:00:00 AM UTC