Modified Julian Day (MJD) ○◂｜appendage｜___｜20260628174208-01-•

Name	Epoch	Calculation	Current value	Notes
Julian date	12:00 January 1, 4713 BC proleptic Julian calendar	JD	2461219.28264
Reduced JD	12:00 November 16, 1858	JD − 2400000	61219.28264	12
Modified JD	0:00 November 17, 1858	JD − 2400000.5	61218.78264	Introduced by SAO in 1957
Truncated JD	0:00 May 24, 1968	floor(JD − 2440000.5)	21218	Introduced by NASA in 1979
Dublin JD	12:00 December 31, 1899	JD − 2415020	46199.28264	Introduced by the IAU in 1955
CNES JD	0:00 January 1, 1950	JD − 2433282.5	27936.78264	Introduced by the CNES3
CCSDS JD	0:00 January 1, 1958	JD − 2436204.5	25014.78264	Introduced by the CCSDS3
Modified JD2000 (MJD2000)	0:00 January 1, 2000	JD - 2451544.5	9674.78264	Introduced by ESA4
Lilian date	day 1 = October 15, 15825	floor (JD − 2299159.5)	162059	Count of days of the Gregorian calendar
Rata Die	day 1 = January 1, 15 proleptic Gregorian calendar	floor (JD − 1721424.5)	739794	Count of days of the Common Era
Mars Sol Date	12:00 December 29, 1873	(JD − 2405522)/1.02749	54207.06273	Count of Martian days
Unix time	0:00 January 1, 1970	(JD − 2440587.5) × 86400	1782586031	Count of seconds,6 excluding leap seconds
JavaScript Date	0:00 January 1, 1970	(JD − 2440587.5) × 86400000	1782586031000	Count of milliseconds,7 excluding leap seconds
EXT4 File Timestamps	0:00 January 1, 1970	(JD − 2440587.5) × 86400000000000	1.7825860309997×10${}^{+18}$	Count of nanoseconds,8 excluding leap seconds
.NET DateTime	0:00 January 1, 1 proleptic Gregorian calendar	(JD − 1721425.5) × 864000000000	639181828309996928	Count of 100-nanosecond ticks, excluding ticks attributable to leap seconds9

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Footnotes

1. Hopkins 2013, p. 257. ↩

2. Pallé, Esteban 2014. ↩

3. Theveny 2001. ↩ ↩²

4. ESA Earth Observation Mission CFI Software Conventions document ↩

5. This is an epoch starting with day 1 instead of 0. Conventions vary as to whether this is based on UT or local time. ↩ ↩²

6. Astronomical almanac for the year 2001, 2000, p. K2 ↩

7. “ECMAScript® 2025 Language Specification”. ↩

8. “2. Data Structures and Algorithms – the Linux Kernel documentation”. ↩

9. “System.DateTime.Ticks documentation”. Microsoft. n.d. Retrieved January 14, 2022. The value of this property represents the number of 100-nanosecond intervals that have elapsed since 12:00:00 midnight, January 1, 0001 in the Gregorian calendar, ↩