[tz] What's "right"?

Steve Allen sla at ucolick.org
Sun Nov 15 23:20:21 UTC 2020

On Sun 2020-11-15T22:31:01+0000 Michael H Deckers via tz hath writ:
> � No, the IAU mean 2017-01-01 - 01 s, a negative value
> � for time of day.

The members of IAU Comm 31 almost certainly did not mean for the time
to have a negative value.

In astronomical almanacs and tabulations it is extremly common to find
date notations like January 0 and October 35.  These notations allowed
tabulations of an entire month to be greatly compacted way back in an
age where every table was typeset by hand and often strained the
margins trying to include all the numbers.  (As an aside, anybody who
eventually wants machines to parse OCR scans of volumes with such
tables is going to have to find (or construct) a date parser which
does not throw errors when it encounters such date notation.)

So for the above case the timestamp would be
where by being in 2017 January it is understood that this time
notation applies to the scale that is continuous after the leap.

Steve Allen                    <sla at ucolick.org>              WGS-84 (GPS)
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