Subject: 3.5m Out of Service starting Dec 1 (tomorrow)

From: Ed Turner

Submitted: Sun, 30 Nov 2003 16:52:05 -0500 (EST)

Message number: 724 (previous: 723, next: 725 up: Index)

I regret to announce that the APO 3.5-meter will be taken out of service
starting tomorrow, Dec 1 2003, for unscheduled/emergency diagnosis and
repair of a problem with the secondary mirror motion actuators.  The 
telescope will be operated tonight (Nov 30) with the scheduled science 
programs but will be shutdown immediately if there are any signs of 
problems with the secondary motions, at the sole discretion of the 
on-duty Observing Specialist(s) of course.

This work is expected to take approximately 5 days, so that the telescope 
could return to science operations as early as the evening of Friday, Dec 
5.  However, there is always a significant uncertainty in such estimates,
depending on the exact nature of the problem, how smoothly the work goes 
and so forth.  A shutdown as along as a week is a reasonable possibility 
as well.

Attempts to move the secondary on recent very cold nights showed 
indications of a significant mechanical malfunction; when temperatures 
warmed on subsequent nights, the problems disappeared.  The goal of this 
unscheduled shutdown is to correct the problem before cold weather returns 
and causes damage that will require a much longer shutdown and perhaps 
considerable expense.

Updates to the situation will be posted to apo35-general as further 
information becomes available.

Ed Turner



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