Re: [LEAPSECS] MJD and leap seconds

From: Rob Seaman <>
Date: Tue, 10 Jan 2006 12:16:41 -0700

On Jan 10, 2006, at 11:06 AM, Poul-Henning Kamp wrote:

> Let me see if understood that right: In order to avoid computing
> problems and to get precise time, astronomers rely on a timescale
> without leapseconds, because the Earths rotation is too unstable a
> clock for their purposes.

Just like everybody else, astronomers rely on interval time when
interval time is needed and rely on earth orientation "time" when
earth orientation is needed. The particular irony is that these two
purposes may be mistaken one for the other.

In a technical arena, there is no more ambiguity here than in many
other issues. Define the requirements for a particular project and
crunch the numbers and design an experiment or apparatus that does
what it needs to do.

In a civil/business/international/legal historical context, one of
the requirements (you will disagree, but please try to make your own
case, not just blow holes in mine) is that only a single realization
of timekeeping may be supported. Ambiguity and conflict are
inevitable as a result. Our goal is to manage the balance between
these appropriately.

Received on Tue Jan 10 2006 - 11:17:37 PST

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