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-May-01-Thu 04:38:45 LT 2460796.69357639 2460797 Local Time Zone TZ +00:00:00 TZ +0.00000000 Universal Time UTC 2025-May-01-Thu 04:38:45 UTC 2460796.69357639 2460797 Delta T Correction +00:01:09 DT +0.00080076 Terrestrial Time TT 2025-May-01-Thu 04:39:54 TT 2460796.69437715 2460797 TAI Correction -00:00:32.184 -0.00037250 Atomic Time TAI 2025-May-01-Thu 04:39:22 TAI 2460796.69400465 2460797 Astronomical JD TT 2460796.69437715 Horizons Delta T +69.185464 sec ============================================================================= ======================================== JD NUMBER TABLE Year:2025 | Month:May Gregorian Calendar Calendar Date JD Number Julian Date Year-Mmm-Dn-DoW JD at 12h JD at 00h ---------------- --------- ----------- 2025-May-01-Thu 2460797 2460796.5 2025-May-02-Fri 2460798 2460797.5 2025-May-03-Sat 2460799 2460798.5 2025-May-04-Sun 2460800 2460799.5 2025-May-05-Mon 2460801 2460800.5 2025-May-06-Tue 2460802 2460801.5 2025-May-07-Wed 2460803 2460802.5 2025-May-08-Thu 2460804 2460803.5 2025-May-09-Fri 2460805 2460804.5 2025-May-10-Sat 2460806 2460805.5 2025-May-11-Sun 2460807 2460806.5 2025-May-12-Mon 2460808 2460807.5 2025-May-13-Tue 2460809 2460808.5 2025-May-14-Wed 2460810 2460809.5 2025-May-15-Thu 2460811 2460810.5 2025-May-16-Fri 2460812 2460811.5 2025-May-17-Sat 2460813 2460812.5 2025-May-18-Sun 2460814 2460813.5 2025-May-19-Mon 2460815 2460814.5 2025-May-20-Tue 2460816 2460815.5 2025-May-21-Wed 2460817 2460816.5 2025-May-22-Thu 2460818 2460817.5 2025-May-23-Fri 2460819 2460818.5 2025-May-24-Sat 2460820 2460819.5 2025-May-25-Sun 2460821 2460820.5 2025-May-26-Mon 2460822 2460821.5 2025-May-27-Tue 2460823 2460822.5 2025-May-28-Wed 2460824 2460823.5 2025-May-29-Thu 2460825 2460824.5 2025-May-30-Fri 2460826 2460825.5 2025-May-31-Sat 2460827 2460826.5 ---------------- --------- ----------- 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