Bug #6042: DateTime::jd off by 12 hours(?)

• Status: Rejected
• Assignee: -
• Target version: -
• ruby -v: 1.9.2-p290

[Steeljack (Dan Martinez)]

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.

[naruse (Yui NARUSE)]

• Status changed from Open to Rejected

As rdoc of DateTime.jd says, its argument is Chronological Julian Day number.