[fitswcs] Draft WCS Paper V: Time

[Steve Allen]

On Tue 2009-04-07T10:55:03 -0400, William Thompson hath writ:
[regarding SN 1054]
> I agree.  There are eclipse records that go back that far.  I've also seen
> papers discussing comet observations from that period or earlier, which discuss
> the possible relationships between those comets and the Kreutz group.

Section 4.1.2.1 of the ISO 8601 standard allows years 0000 through
1582 by "mutual agreement", so the language of the current draft uses
"proleptic Gregorian" and Herschel to make that usage explicit.

Section 3.5 of the ISO 8601 standard allows years prior to 0000 or
after 9999, again by "mutual agreement".  The current draft does not
attempt to define these.  Any such dates prior to 1583 could not have
been in contemporary use, and it is pure hubris to specify 8 millennia
into the future.

Given that such calendar dates either require translation from the
contemporary record, or prediction of social norms, the authors
are of the impression that the extension of section 3.5 is not
necessary.  The JD form is not required to be positive, but even
the positive values cover all alphabetic human records.

Getting serious about this, we need input on how important this
calendrical application is.

Should the paper attempt to require that parsers of DATExxxx keywords
be prepared to accept formats where the year is either negative or
8 millennia into the future?

--
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