Re: [LEAPSECS] GMT -> UTC in Australia

From: Rob Seaman <seaman_at_NOAO.EDU>
Date: Thu, 24 Feb 2005 12:31:20 -0700

> There have been genuinely secular changes in zone, call them silly or
> not: Pacific/Enderbury (Phoenix Islands Time) changed its time zone
> from -11:00 to +13:00 in 1995, and Asia/Kashgar (extreme
> western China) changed its time zone from -5:00 to -8:00 in 1980-05
> (its LMT is 5:03:56).

Not silly - and not secular. Astronomers (at least) use the term
"secular" to imply monotonic - and therefore cumulative - effects. The
TZ changes mentioned are merely examples of single isolated events.
Whether they make sense is a local decision. Are we really suggesting
that local decisions are improved by ignorance?

Perhaps part of the confusion is between definitions (for example, from
m-w.com):

     3a : occurring once in an age or a century

Which is perhaps what Mr. Cowan means, and what the advocates of
tolerance for bad temporal system design are certainly relying on. As
opposed to what I mean:

     3b : existing or continuing through ages or centuries

The Earth's rotation will continue to slow (as a general trend) whether
we ignore this fact or not. If we are choosing to ignore it, for god's
sake at least don't bastardize the name "UTC" to mean something
different than every other flavor of Universal Time. UTC is a useful
approximation to GMT. Keep it that way and call any new system of
civil time that might win the day something else. It is the height of
intellectual dishonesty to do otherwise.

Rob Seaman
National Optical Astronomy Observatory
Received on Thu Feb 24 2005 - 11:32:10 PST