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Re: [ISO8601] New version ISO 8601:2005 released 2005-04-01

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  • John Steele
    I m sure astronmers everywhere would have preferred Julian Days, ie 245 3461.500 John Hynes wrote: The new version of the ISO 8601 standard is
    Message 1 of 3 , Apr 1, 2005
      I'm sure astronmers everywhere would have preferred Julian Days, ie 245 3461.500

      John Hynes <john@...> wrote:

      The new version of the ISO 8601 standard is being released today,
      2005-04-01.000. 
    • John Hynes
      ... Astronomers also use Gregorian dates, in year-month-day order, with the fractional day added to the ordinal day of month. For instance, the standard epoch
      Message 2 of 3 , Apr 1, 2005
        --- John Steele <johnmsteele@y...> wrote:
        > I'm sure astronmers everywhere would have preferred Julian Days, ie
        > 245 3461.500

        Astronomers also use Gregorian dates, in year-month-day order, with
        the fractional day added to the ordinal day of month. For instance,
        the standard epoch J2000.0 is often represented as 2000 January 1.5,
        which would be 2000-01-01,5 in ISO format. I can provide many
        examples online. Also, NASA and NORAD publish epoch dates of orbital
        elements of artificial satellites as ordinal dates with fractional day
        added, e.g. the same date is represented as 00001.50000000. (Still
        with two-digit year, unfortunately.) It would make sense to
        incorporate this practice by astronomers into ISO 8601. Although the
        month is usually spelled out or abbreviated, the month number is also
        used sometime. The ISO standard does cover decimal fractions of
        hours, minutes and seconds, but not days.

        I suppose that Julian Dates could be added to the ISO 8601 standard,
        but that would seem unnecessary, since they are represented simply as
        a single decimal number. It would be a short section. I think that
        fractional day s are used by astronomers, instead of HMS, for ease in
        calculations, including the converstion to/from JD/MJD. Julian Days
        and Julian Dates, as well as Modified Julian Dates, already are
        covered by a standard, IAUGA XXIII Resolution B1.

        And if anybody hasn't figured it out by now, April Fool! I figured
        that this group might get a kick out of it. :)

        John
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