[LEAPSECS] Pre-1972 UTC
sla at ucolick.org
Mon Feb 16 19:38:03 EST 2009
On Mon 2009-02-16T23:22:49 +0000, Tony Finch hath writ:
> > http://cm.bell-labs.com/cm/cs/who/dmr/1stEdman.html
> Which says that Unix time settled on its current rate and epoch in 1973,
> so there won't be timestamps from before then.
And that means that the POSIX epoch encompasses almost as much
proleptic fantasy as the use of UTC (or GMT) for the 1601 epoch. The
observatory at Greenwich wasn't commissioned for another 75 years, not
until after 3 coronations and a civil war. I barely want to mention
Microsoft's use of the 0001 epoch in .NET
> I'd expect astronomers to have some.
Yes, thousands of them. The ones with that sort of precision are
almost every observation made by the transit circles -- many of those
being the ones which Newcomb used to create his Tables of the planets
and expression for UT -- many of which are still the inputs Standish
selected for the JPL planetary ephemerides.
Those stand together with the timed occultations used by Morrison and
Stephenson and collaborators to calibrate the nonuniformity of UT.
Steve Allen <sla at ucolick.org> WGS-84 (GPS)
UCO/Lick Observatory Natural Sciences II, Room 165 Lat +36.99855
University of California Voice: +1 831 459 3046 Lng -122.06015
Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m
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