[LEAPSECS] What's the point?

Ian Batten igb at batten.eu.org
Tue Feb 15 06:19:11 EST 2011

On 15 Feb 11, at 1011, Poul-Henning Kamp wrote:

> In message <20110215100536.GD78376 at davros.org>, "Clive D.W. Feather" writes:

>> Poul-Henning Kamp said:


>>>> The UK's standard time broadcast, which is funded by the government,

>>>> contains DUT1 in a format which doesn't permit |DUT1|>0.9. Whatever

>>>> people argue (rightly) about the de facto legal time in the UK being

>>>> UTC, the de jure legal time is "GMT" which is taken to be UT1.


>>> Where and by who is that "taken to be UT1" ?


>> Just about everyone.


> Really ?


> In that case, please provide us with 10 examples of "everyone."

Parliament will do: the contention went unopposed when made in the house of lords. You are referred to the second reading in the House of Lords of the Co-ordinated Universal Time Bill, which you will find in Hansard 11 Jun 1997 Column 965, for an overview which picks up from the Interpretation Act 1978, as Cive points out.

To define GMT, I'll take ITU TF460, Annex 1, which states:

Universal Time (UT) is the general designation of time scales based on the rotation of the Earth...UT1 is used in this document, since it corresponds directly with the angular position of the Earth around its axis of diurnal rotation. (GMT may be regarded as the general equivalent of UT.)

But just in case the ITU don't impress you, I'll take theNational Measurement System Directorate, DTI, writing in April 2005 (http://www.npl.co.uk/upload/pdf/20050415_t-f_lee_1.pdf) --- NPL is as close to ex cathedra as the UK scientific establishment gets:

Mean Solar Time = UT1 = GMT:
Used as the basis of civil time in the UK and other countries: derived from the apparent movement of the sun.


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