JulianDate

JulianDate[]

gives the current number of days since noon on November 24, 4714 BCE in the GMT time zone.

JulianDate[date]

gives the number of days for the specified date.

JulianDate["type"]

gives the Julian date variant of the specified type.

JulianDate["type",date]

gives the variant for the specified date.

Details

  • In JulianDate[date], date can be a DateObject, a date string, a {y,m,d,h,m,s} date list, or a number corresponding to an absolute time specification.
  • JulianDate[date] assumes that the given date is in $TimeZone, unless it is a DateObject or TimeObject with an explicit TimeZone option value.
  • The result of JulianDate is a number of days, including a fractional part giving the time since the previous noon in GMT.
  • Shorter lists can be used in JulianDate[{y,m,…}]: {y} is equivalent to {y,1,1,0,0,0}, {y,m} to {y,m,1,0,0,0}, etc.
  • Values of m, d, h, m, s outside their normal ranges are appropriately reduced. Noninteger values of d, h, m, s can also be used.
  • Possible Julian date variants include:
  • "Reduced"relative to noon on November 16, 1858
    "Modified"relative to midnight on November 17, 1858 (MJD)
    "Truncated"relative to midnight on May 24, 1968 (TJD)
    "Dublin"relative to noon on December 31, 1899 (DJD)
    "Full"relative to noon on November 24, 4714 BCE (JD)
  • The default Julian date variant used is "Full". All referenced dates are using the proleptic Gregorian calendar.

Examples

open all close all

Basic Examples  (3)

Julian date in days since noon November 24, 4714 BCE:

In[1]:=
Click for copyable input
Out[1]=

Julian date variants have different epoch dates:

In[2]:=
Click for copyable input
Out[2]=
In[3]:=
Click for copyable input
Out[3]=

Convert from a date object to a Julian date:

In[1]:=
Click for copyable input
Out[1]=
In[2]:=
Click for copyable input
Out[2]=

Convert from a date string to a Julian date:

In[1]:=
Click for copyable input
Out[1]=
In[2]:=
Click for copyable input
Out[2]=

Scope  (6)

Properties & Relations  (3)

Introduced in 2015
(10.2)