On Wed 2013-09-04T14:40:57 -0700, Paul Eggert hath writ:
Yeowch! You're right; sorry about that. I should have written "GMT". I was misled by zdump's output.
Except that GMT prior to 1925 means one thing for civil timestamps and a different thing for nautical timestamps.
Should we change the output of "zdump" etc to fix this error? Currently zdump says "UTC" for old time stamps, which isn't correct. Should it say "UT" instead? Or is even "UT" a bad idea for a time stamp in (say) 1627?
Unlike UTC, the concept of UT can be validly extended into the indefinite past.
I also should have mentioned that even with GMT, my comment was incorrect in some sense. Common practice back then for Dutch possessions was to use non-integer offsets from GMT, and the tz format cannot represent these. I don't have good data for Aruba, but Capt. Thomas Henry Tizard of the Royal Navy reported that Curacao's port kept time at -04:35:46.9; see Milne 1899.
One might argue over the validity of the conventional formula for UT being used in the far past, and for the purposes of geodesy it is relevant to be precise, but to the relevant precision for civil timestamps any reasonable conventional expression for UT is as valid as the timestamps themselves. -- Steve Allen <sla@ucolick.org> WGS-84 (GPS) UCO/Lick Observatory--ISB Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m