Re: [LEAPSECS] Pre-1972 UTC seconds and days

From: Ed Davies <>
Date: Fri, 27 Jun 2003 11:19:42 +0100

Thanks to Steve Allen, Joseph Myers and Jim Ray for comprehensive
answers to my two recent questions.

I wrote:

> > ... did
> > TAI-UTC vary during the course of a single UTC day?

Steve Allen replied:

> For practical purposes it still does. See

Well yes, though this rather depends on your definition of
"practical". There is a significant difference between
millisecond level trends in the *definition* of UTC relative
to TAI and sub-microsecond level wobbles in particular
*implementations* of UTC. For many applications the best
available approximation to UTC, from the 1PPS output of a GPS
receiver, is at the microsecond level anyway.

Received on Fri Jun 27 2003 - 03:20:44 PDT

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