method modified-julian-date

Documentation for method modified-julian-date assembled from the following types:

class DateTime

From DateTime

(DateTime) method modified-julian-date

Defined as:

method modified-julian-date(DateTime:D: --> Real:D)

Returns the Modified Julian Date (MJD) for the UTC date and time.

say'2021-12-24T12:23:00.43Z').modified-julian-date# OUTPUT: «59572.5159772␤»

Notice the fractional part of the modified-julian-date is same value as the day-fraction for the same instant. Likewise, the integral part of the MJD is the same value as the daycount for the same instant since they reference the same epoch (November 17, 1858). The MJD is obtained by subtracting the constant 2_400_000.5 from the Julian Date and is used to simplify transformations between civil and astronomical time systems.