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 2017-01-00T23:59:59 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@ucolick.org> WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m