[LEAPSECS] Telescope pointing and UTC, was: Re: What I do. What do you do?

From: Ed Davies <ls_at_EDAVIES.NILDRAM.CO.UK>
Date: Wed, 29 Jan 2003 15:14:14 +0000

Steve Allen wrote:
> ...
> 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. ...

Out of curiousity, where do these systems get UTC from? Broadcasts
like WWV or GPS, via NTP or someplace else? I assume there is a
local, reasonably accurate, clock which is corrected from the
external source.

Also, do they actually use UTC as an approximation to UT1 or do they
correct UTC to UT1 but just have some built in assumption that the
correction will be less than one second? If they make the correction,
where do they get UT1 - UTC from? Is it entered manually?

Ed Davies.
Received on Wed Jan 29 2003 - 07:14:59 PST