Re: [LEAPSECS] Mechanism to provide tai-utc.dat locally

From: M. Warner Losh <imp_at_BSDIMP.COM>
Date: Thu, 28 Dec 2006 22:07:08 -0700 (MST)

In message: <>
            Rob Seaman <> writes:
: M. Warner Losh wrote:
: > Let's turn the question around. What would the harm be if |DUT1| were
: > 1.1s? 1.5s? 2.0s? Contrast this with the harm and difficulty that
: > the current 6 month scheduling window affords.
: Indeed. Go for it. I look forward to reading your report. Who and
: what interests are adversely affected in each case? How are these
: effects mitigated as a function of the limit on DUT1? Also, contrast
: what benefits accrue. One would think that the responsibility for
: quantifying the implications of a change to a standard would fall on
: the parties proposing said change.

I know the benefits, but nobody has yet produced a study on why 0.9s
was chosen. Some vague rumblings about astronomical software needing
to be rewritten, and some vague notions about 'hearty souls' that do
celestial navigation with atomic clocks for high accuracy have been
offered, but who really would be hurt by this change? Since you are
an astronomer, I thought you might be able to give some insight into
at least one of these users of time. Daylight savings time and time
zones prove that society at large has a very high tolerance for
variations between the mean solar time at an arbitrary location, maybe
hundreds of miles away, and the local time. Only specialized users of
time would be affected. Who are they and how do we find out the cost
of change?

The world has changed from having maybe a few dozen or tens of dozen
atomic clocks when leap seconds started to having GPS with cheap,
disciplined oscillators that number in the hundreds of thousands.
These little devices have obviated the need, in many cases, for
celestial navigation. Given that change, the cost benefit analysis
that was done in 1972 likely needs updating.

Received on Thu Dec 28 2006 - 21:10:02 PST

This archive was generated by hypermail 2.3.0 : Sat Sep 04 2010 - 09:44:55 PDT