# 2.1.11 Dates and Times in Origin

Origin interprets dates based upon the Gregorian Calendar. Time is interpreted in hours:minutes:seconds. Origin supports the following date ranges:

• When entering four digits for the year, Origin supports a date range of:
1/1/0100 to 12/31/9999.
• When entering two digits for the year, Origin supports a date range of:
0 to 44 = 2000 to 2044
45 to 99 = 1945 to 1999

Origin's mathematical system for date and time is based on the astronomical Julian Day, which defines January 1, -4712 (January 1, 4713 BCE), 12 hours Greenwich Mean Time as zero. Note that Origin uses a -12 hour offset in order to have 0 hours coincide with midnight. When you read the phrase Julian-date value in the Origin documentation, you should understand that this refers to Origin's value, which includes the -12 hour offset. No assumptions are made about time zones or any time shifting scheme (such as Daylight Savings).

In this system, for example, Origin interprets ...

11 June 1998 at 21:23:01

... as a date value of ...

2450975.890984.

To obtain the astronomical Julian Date, we add 0.5 (to account for Origin's -12 hour offset), yielding a value of 2450976.390984.

For more information on Origin's Date and Time formats, see these topics:

Reference: Wikipedia contributors, "Julian day," Wikipedia, The Free Encyclopedia, https://en.wikipedia.org/wiki/Julian_day.