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Re: [Gnu-arch-users] s/GMT/UTC/
From: |
Jan Hudec |
Subject: |
Re: [Gnu-arch-users] s/GMT/UTC/ |
Date: |
Tue, 7 Sep 2004 14:15:05 +0200 |
User-agent: |
Mutt/1.5.6+20040818i |
On Tue, Sep 07, 2004 at 13:06:39 +0200, Juliusz Chroboczek wrote:
> Folks, you're confusing GMT with TAI.
I don't think so. But anyway, the definitions go roughly like this:
GMT (or UT, UT1) is a clock code of the mean sun in Greenwich. A mean
sun is an imaginary celestial object, that coincides with Sun on
spring equinox. Second in GMT is 1/86400 day and since Earth
rotation is not uniform, neither is GMT second.
TIA is a time measured by by atomic clock. It uses the SI second defined
as some number of Cs oscilations and is MEASURABLY SHORTER than mean
solar second (used in GMT). There is no SI minute, SI hour, SI day
etc. TIA is just plain number of seconds since some point in time.
UTC is a time that uses SI seconds, but it synchronizes with GMT by
insertion/omiision of a leap second whenever it diverges by more
than 0.9s.
POSIX and NTP times tick in SI seconds, but they ignore the leap
seconds. Thus while the clock ticking is monotonous, intervals are
computed in mean solar seconds.
-------------------------------------------------------------------------------
Jan 'Bulb' Hudec
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- [Gnu-arch-users] s/GMT/UTC/, Zenaan Harkness, 2004/09/06
- Re: [Gnu-arch-users] s/GMT/UTC/, Andrew Suffield, 2004/09/06
- Re: [Gnu-arch-users] s/GMT/UTC/, John Meinel, 2004/09/06
- Re: [Gnu-arch-users] s/GMT/UTC/, Phil Frost, 2004/09/07
- Re: [Gnu-arch-users] s/GMT/UTC/, Cameron Patrick, 2004/09/07
- Re: [Gnu-arch-users] s/GMT/UTC/, Andrew Suffield, 2004/09/07
- Re: [Gnu-arch-users] s/GMT/UTC/, Cameron Patrick, 2004/09/07
Re: [Gnu-arch-users] s/GMT/UTC/, Jan Hudec, 2004/09/07
Re: [Gnu-arch-users] s/GMT/UTC/, Jeremy Shaw, 2004/09/07
Re: [Gnu-arch-users] s/GMT/UTC/, Jan Hudec, 2004/09/07
[Gnu-arch-users] Re: s/GMT/UTC/, Miles Bader, 2004/09/07