Re: [LEAPSECS] BBC - Leap second talks are postponed

From: Ed Davies <ls_at_edavies.nildram.co.uk>
Date: Fri, 18 Nov 2005 11:10:12 +0000

David Harper wrote:
> ....
> The experiment was abandoned in October 1971, when the clocks were put
> back to Greenwich Mean Time,

Out of historical interest, anybody know if this was true, or were
the clocks actually put back to UTC? I.e., when did MSF, etc, switch
from GMT to UTC?

By the way, this was just before the point when UTC switched from
rubber seconds to leap seconds. In October 1971 UTC days were
86 400.002 592 TAI seconds long. This was true until the first of
January 1972 when UTC seconds became the same length as TAI ones.

> ....
> It's true that the GMT/BST naming scheme does not conform to the
> Standard Time/Daylight Time pattern, but GMT is equivalent to Western
> European Standard Time

I've not heard the terms WEST and WEDT used before but assume this
is right to +/-0.9 seconds

> and BST to Western European Daylight Time.

Yes, that sounds right, exactly.

> However, it would be a brave and foolhardy M.P. who proposed in
> Parliament that the names GMT and BST should be abolished and replaced
> by WEST/WEDT. That would generate a far greater furore in British
> politics than any discussion about leap seconds :-)

I thought GMT already had been abolished for practical purposes.
It's a pity that the name continues to be misused. However, as
Rob Seaman has pointed out in a separate thread:

> If you want to propose an international civil
> time standard without leap seconds, start by calling it something
> other than UTC. Leap seconds are intrinsic to the concept of UTC.

I agree with most of what Rob says in that message and especially
with this. If there's any possibility of the basis of civil time
not being one of the UT timescales then it should be given a
different name.

Getting everybody to change from saying "GMT" to "UTC" to then
tell them to change to something else seems like the sort of
thing which causes irritation with technical and bureaucratic
people.

On the other hand, I rather snigger at the reservation of the
word "universal" to mean time based on the Earth's rotation.
It's all rather parochial but it is the established terminology.

Ed.
Received on Fri Nov 18 2005 - 03:12:43 PST