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Bug #6042

closed

DateTime::jd off by 12 hours(?)

Added by Steeljack (Dan Martinez) over 9 years ago. Updated over 9 years ago.

Status:
Rejected
Priority:
Normal
Assignee:
-
Target version:
-
ruby -v:
1.9.2-p290
Backport:
[ruby-core:42707]

Description

I am deeply reluctant to file a bug against something so fundamental as DateTime, and wonder whether I might have missed something, but:

When passed an integral value, DateTime::jd returns a DateTime object whose time is set to midnight GMT:

puts DateTime.jd 2455972
2012-02-14T00:00:00+00:00

The WikiPedia entry for "Julian Day" reads, in part: "Julian day is used in the Julian date (JD) system of time measurement for scientific use by the astronomy community, presenting the interval of time in days and fractions of a day since January 1, 4713 BC Greenwich noon."

It therefore seems to me that a whole number of days since that time would itself necessarily fall on Greenwich noon.

Please feel free to tell me that I'm missing something blindingly obvious.

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