Re: [LEAPSECS] TAI-UT1 prediction

From: Markus Kuhn <Markus.Kuhn_at_CL.CAM.AC.UK>
Date: Thu, 20 Jan 2005 18:29:43 +0000

Tom Van Baak wrote on 2005-01-20 17:33 UTC:
> No one can know for sure but I was wondering if
> there is a consensus on when the first leap hour
> would occur?

A good table summary of some projections is in

  http://www.ucolick.org/~sla/leapsecs/dutc.html#dutctable

and other discussions are on

  http://www.ien.it/luc/cesio/itu/ITU.shtml

and there in particular in

  Prediction of Universal Time and LOD Variation - D. Gambis and C. Bizouard, (IERS)
  http://www.ien.it/luc/cesio/itu/gambis.pdf

> Even to an order of magnitude? I
> ask because the above document draft says "at
> least 500 years" while others here cite numbers
> like 600 years, or 5000 years.

5000 years until the next leap second sounds like someone got some very
basic maths wrong (by then, a whole leap day would be due), the other
two figures sound feasible. Perhaps a confusion about the rotation of
earth (UT1 clock frequency) slowing down roughly linearly, therefore the
accumulation of the phase difference being (after integrating) an
essentially quadratic function?

Markus

--
Markus Kuhn, Computer Lab, Univ of Cambridge, GB
http://www.cl.cam.ac.uk/~mgk25/ | __oo_O..O_oo__
Received on Thu Jan 20 2005 - 10:30:07 PST

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