Re: Pre-1972 UTC seconds and days

From: Steve Allen <>
Date: Sun, 29 Jun 2003 22:46:05 -0700

On Thu 2003-06-26T08:36:57 -0700, Steve Allen hath writ:
> On Thu 2003-06-26T12:15:09 +0100, Ed Davies hath writ:
> > Here's the question: was a UTC second the same as an SI second
> > so that days were a non-integral number of UTC seconds or was
> > the UTC second slightly longer than the SI second?
> The best table that I've seen for this applies only to the WWV
> transmissions in the US, and it is located on pages 86-87 of the
> Explanatory Supplement to the Astronomical Almanac edited by P.K.
> Seidelmann.

Aha! Online the USNO has this table for UTC from 1961 onward.
(prior to that there was no UTC, so the WWV offsets in the
Expl.Supp. are applicable only near the US).

It does not explicitly indicate the magnitudes of the step offsets
to UTC as in the Expl.Supp., but it does clearly show the changes in
the length of a UTC second.

Steve Allen          UCO/Lick Observatory       Santa Cruz, CA 95064      Voice: +1 831 459 3046
PGP: 1024/E46978C5   F6 78 D1 10 62 94 8F 2E    49 89 0E FE 26 B4 14 93
Received on Sun Jun 29 2003 - 22:46:18 PDT

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