Re: [LEAPSECS] Problems with GLONASS Raw Receiver Data at Start of New Year

From: Rob Seaman <seaman_at_noao.edu>
Date: Sat, 14 Jan 2006 16:20:28 -0700

On Jan 14, 2006, at 11:20 AM, John Cowan wrote:

> I'd expect to see a wave of breakage as DUT1 exceeded 0.9s for the
> first time, and a second wave as it exceeded 1s for the first
> time. After that, of course, the problems would no longer be
> relevant. :-)

I haven't been able to decipher what the humor is meant to be here -
will gladly admit that this is likely a failure on my part. I won't
ask you to explain the joke, but rather I suspect you had a more
basic point you were seeking to make. Is there some reason that
risks resulting from a diverging DUT1 can be expected to be mitigated
(even in part) as it grows past 1s?

If we discount the melodramatics of this list (will gladly admit to
being one of the offenders), we are left with a rather interesting
technical discussion of how best to deliver both interval time and
earth orientation information to a variety of classes of users.
Whatever the context of that discussion and of our own personal
points of view, one large element of confusion is precisely that TAI
mimics UTC mimics GPS mimics... We might more easily recognize the
distinct character of each time-scale if neither their values or the
representations of those values permitted them to masquerade one for
the other.

Atomic Time is naturally represented as an unending count of
seconds. Universal Time is naturally represented as a fraction of a
day (equivalent to an angle). It is that naive heuristics exist that
claim to convert Atomic Time into fractional days - or alternately,
to convert Universal Time into a count of seconds - that creates
confusion between the two.

Rob Seaman
NOAO
Received on Sat Jan 14 2006 - 15:20:44 PST