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# Modified Julian Day (MJD)

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Equation / Last modified by Administrator on 2015/10/23 00:39
`MJD = `

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MichaelBartmess.Modified Julian Day (MJD)

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This equation gives you the Modified Julian Day (MJD) when you input a Gregorian (standard modern calendar date).

The MJD's starting point epoch is midnight on November 17, 1858.

"The **Modified Julian Date** (MJD) was introduced by the Smithsonian Astrophysical Observatory in 1957 to record the orbit of Sputnik via an IBM 704 (36-bit machine) and using only 18 bits until August 7, 2576. MJD is the epoch of OpenVMS, using 63-bit date/time, postponing the next Y2K campaign to July 31, 31086, 02:48:05.47."^{1}

**Example**

If you input **January 1, 2000**, this equation will return the Julian Day: **51544.5**

If you input **November 17, 1858**, this equation will return the Julian Day: **0.5**

**See Also**

# References

This equation,

**Modified Julian Day (MJD)**, references 3 equations/constants.**Equations and Constants **

This equation,

**Modified Julian Day (MJD)**, is used in 1 calculator.**Calculators**