[LEAPSECS] UT1 via NTP

[Steve Allen]

On Wed 2018-03-21T08:51:37-0700 Steve Allen hath writ:
> Our robotic telescope with small FOV on the guider does better if it
> is given UT1 to 0.1 second.  That telescope grabs the USNO predictions
> of EOP every week to update the pointing.

I'll add that I do not see any place where I would want to use UT1 via
NTP for astronomical observations.  The real-time operation of the
telescopes does not want to be dependent on a very small number of
external real-time sources over telecomm links that can fail.

That is why we rely on the USNO predictions, for they give us several
months of lookahead.  Thus also we have several months of warning if
the USNO decides to stop publishing EOP, and that is enough time to
engineer a replacement source of information.

It was not happy when DoD was doing theater-level jamming near Hawaii
and the Keck telescope GPS time servers had dates that were completely
insane.  In that case the local system clocks retained sanity for the
duration of the jamming.  In extension of all this I argue again that
what is really wanted is a source of Atomic Time that is completely
robust plus a widely disseminated source of tabular or polynomial
predictions of Atomic Time minus Universal Time.

--
Steve Allen                    <sla at ucolick.org>              WGS-84 (GPS)
UCO/Lick Observatory--ISB 260  Natural Sciences II, Room 165  Lat  +36.99855
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