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

From: Rob Seaman <>
Date: Mon, 21 Nov 2005 09:05:17 -0700

On Nov 21, 2005, at 1:53 AM, Clive D.W. Feather wrote:

> It is NOT CALLED "daylight saving" and it is NOT saving any daylight.
> It is "summer time".

Ok, then. Anybody have a suggestion for a general term for which
daylight saving and summer time are special instances? My argument
still holds, however. DS/ST are modifiers of the underlying standard
time concept. Introducing a completely different nomenclature for
half the year guarantees confusion. Cross timezone video conferences
are a daily occurrence in my organization. There is a bit of
residual ambiguity twice a year, but the rest of the time we don't
have to distinguish between standard time and daylight saving, but
rather just refer to "o'clock in Chile" or "the time in Hilo or
Maryland". In fact, note that this is true even though two of the
endpoints don't use DS at all and one has inverted DS because it's in
the southern hemisphere. Which is to say that GMT is indeed tripping
you up because it isn't just a label for your timezone, but has a
more fundamental role as the zero point of the international system.

>> Contrarily, in Britain you have chosen to call your civil standard
>> time "Greenwich Mean Time"
> That being because it is the Mean Time at Greenwich.

Imagine constructing an ontology of time. "Mean Time at Greenwich"
is a distinct concept from "Standard Time in Britain".

>> and your civil daylight saving time "British Summer Time",
> Correct, that because it's the time in the summer in Britain.

A fine name - except that it implies unnecessary restrictions on
public policy. You appear to share my opinion that DS/ST is - well -
kinda dumb. But obviously others disagree. The policy makers could
just as easily decide to set the clock back from the standard in the
winter. Or decide to implement any number of other scheduling
algorithms. This would be (relatively) trivial with "daylight
saving". It would be rather harder to sell as "summer time".

> British Standard Time is something else.

You piqued my curiosity - an interesting experiment: http:// Also see http://

But fine. Instead of British Summer Time, call in Greenwich Summer
Time. Then your boss could simply reference "Greenwich Time" or GT
all year round. Actually, we rarely refer to Eastern Standard Time
OR Eastern Daylight Time, but rather simply Eastern Time.

> And British Daylight Time is, I would guess, the opposite of
> British Nighttime Time.

The world is full of limp nomenclature. Certainly nothing we've ever
discussed in this group approaches the extremes of usage that are
tolerated (in English, in "American", or it is to be expected, in
other languages).

On Nov 21, 2005, at 2:58 AM, Poul-Henning Kamp wrote:

> The Danish version talks about UTC, which is cute since in Denmark
> legal time is still mean solar time at the Copenhagen Observatory,

How does this work in practice? Lots of web hits show Copenhagen in
the Central European Timezone, one hour ahead of Greenwich (ignoring
the whole summer time issue). Its longitude appears to be 12.66
degrees east, or 50 minutes ahead.

Rob Seaman
National Optical Astronomy Observatory
Received on Mon Nov 21 2005 - 08:06:15 PST

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