Date: Mon, 10 May 1999 03:37:21 -0600 (MDT)
From: hayes@apo.nmsu.edu
Subject: 2.5 m obslog 990509 (MJD 51308)
			Sunday May 9, 1999
		Apache Point Observatory SDSS 2.5m
			     Observing Log
Observing Team:
		Jeffrey Hayes (APO)
		Ellyne Kinney (APO)
		Bob Nichol (CMU)
                Matt Newcomb (CMU)
                Connie Rockosi (UC)
Weather:  Clear and rising dust.  Very windy: ~29 mph steady and gusts
up to 35 mph.  We waited till 21:30 MDT to open after the winds died
down.
We forgot to mention in last night's log that the 15 degree stop behaved
as advertized all night.  Save for the one incident we saw early in the
evening.
We believe that part of our problem last night while trying to get the
guiding to work consistantly was that by the time we got on track,
the K field was well over to the west so that the local offset correction
and the differential atmospheric refraction were killing us.  We have found
an FK5 star pretty much in the K field now, so this should not be a problem.
We started our session by slewing to the FK5 star and finding it in the
fibre!  We tried to use the finder telescope to update the pointing
model, but it appears to be out of alignment as the offsets we tried
where very large, we could not find the star, and couldn't centre the star
in the fibre.  We then tried a blind pointing without using the finder
telescope and trusting the pointing model.  This time, success!  We then
tried to focus the star.  We found that optimal focus tonight was
4000 --- much higher than expected.  We note that at this point the
weather started to deteriorate -- steady winds up to 30 mph and gusts
to 39 mph.  It was at this point that we closed at 23:00 MDT.  We have
taken a series of short integrations of the FK5 star to see how well
the telescope holds up in high winds.  These data are to be analysed
to see if we should modify the current closure conditions (which are
opening for sustained winds under 25 mph, and gusts less than 30 mph:
closing are gusts of 35 mph and above).  We note from direct observation
though, that the building around the pier does move with gusts higher
than about 30 mph.
We did try and open at 02:30 MDT, but by 03:00 MDT there were continuing
gusts over 30 mph, and the dust at 1 micron spiked over 3000 PpCF.  At
03:30 MDT we decided to end the attempts to open.
Jeffrey