Re: What I do. What do you do?

From: Steve Allen <>
Date: Wed, 29 Jan 2003 01:29:55 -0800

On Tue 2003-01-28T16:31:03 -0700, Rob Seaman hath writ:
> A useful exercise from other mailing lists and conferences and such
> is simply to get to know each other and how we all fit into the puzzle
> under discussion.

Without listing details, point by point my job is largely the same as
Rob's except that I work for a state-funded agency that manages
venerable equatorial mount telescopes in California and co-manages the
largest az-alt mount binoculars in the world in Hawaii.

I am an astronomer paid to write code, and I am more familiar with
coordinates, timescales, and protocols than many. Among the student
team who assisted with computer system management during my
undergraduate days I am infamous for the "Steve Allen Memorial Gripe"
when I submitted the report that the system clock was wrong by two
minutes. I put NTP onto our local systems long before the OS vendors
were supplying it as a default element of the system. I inserted
language when the FITS standard revised its notions of date/time.

> The notion of discarding the connection between UTC and GMT is not
> just philosophically distasteful - it clearly would make my job more
> difficult for zero benefit.

For more than 20 years the Mt. Hamilton telescopes have been pointed
by a system that runs off a multitasking, 8-bit, 6502 processor. Lick
is currently constructing the replacement for this system and also
contracting with an outside agency to supply the pointing system for a
new telescope. These systems are expected to last for many decades.
Neither of these systems expects UTC - UT1 > 1 second. Even if a
concrete proposal for handling the side effects of abolishing leap
seconds were available now, it would be too late for these new

For the sake of those whose systems are not yet as concrete as ours
the possibility that leap seconds might cease means that the
watchwords should be proclaimed:

    Do not presume that the value of (UTC - UT1) will remain negligible.
    Make the value of (UTC - UT1) into an inputtable parameter.

This is somewhat useless as a specification in the absence of a
definite future standard, but it relatively safely presumes that
something called UTC will remain easily available (as now) and that
the value of (UTC - UT1) will (continue to) change slowly enough that
it can, if necessary, be put in manually.

Steve Allen          UCO/Lick Observatory       Santa Cruz, CA 95064      Voice: +1 831 459 3046
PGP: 1024/E46978C5   F6 78 D1 10 62 94 8F 2E    49 89 0E FE 26 B4 14 93
Received on Wed Jan 29 2003 - 01:30:10 PST

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