Date: Wed, 3 Mar 1999 06:36:29 -0700
From: long@apo.nmsu.edu (Dan Long)
Subject: 2.5m obslog 990302
                           TUESDAY MARCH 2, 1999
                     APACHE POINT OBSERVATORY SDSS 2.5m
                              OBSERVING  LOG
   The enclosure was opened at about 17:30.  The engineering camera was
remounted on the telescope.  The telescope was set up on the meridian at
the equator.  All in all a very productive night despite a slow start.  We
routinely got .75 arcsecond images when the astigmatism corrector was
turned on.  Once we got .65"!!
   We had communication troubles with camera.  Computer hang and apparently
false OK signals from Paralans had us looking in the wrong places for quite
a while.  It seems that there was a connection problem with the fibers.
Could have been a seating problem, could be an intermittent connection in
one of the fibers.  However once the connectors on the camera end were
fiddled with, we had no further communication problems.
   Started collecting data at 22:00.
   There was a strange seeing event where fwhm went from around an
arcsecond to nearly five, then back to sub arcsecond over the course of an
hour and a half between 23:00 and 00:30.  Wind speed and direction remained
consistently from the SSW at 10 to 15 MPH, and so the usual culprit of an
easterly wind shift can't be blamed.
   Despite the unusually variable seeing, we got good primary
tilt/translation values.
setmir:  0  -31.3  13.3  726  1708
galil: 6660 -3787  -271 14476  17552 17038
linear gauges:  1.9260  .5610  .5580  .3460  1.9195  .4195
We fired up the astigmatism corrector with the proper position angle ( see
values below
Meter settings for astigmatism amplitude 230 nm, PA 109.5 degrees
  chan   pos ang   setting
    1     349.5     146.9
    2     319.5      53.1
    3     289.5       6.2
    4     259.5      53.1
    5     229.5     146.9
    6     199.5     193.8
    7     169.5     146.9
    8     139.5      53.1
    9     109.5       6.2
   10      79.5      53.1
   11      49.5     146.9
   12      19.5     193.8
When we went for best focus we got an fwhm of .65 arcseconds!!  Most best
focus images for the rest of the night were around .8" or less.
Astigmatism is significantly reduced, though some small amount remains in
the same orientation as before the corrector was turned on.
  We also took data at 77 and 37 degrees and they looked good ( though the
seeing at 37 deg was worse at about 1.3 arcseconds or so ).
Note:  The azimuth stow position light comes on in two places in azimuth,
separated by about 6 degrees or so.  The proper position is the higher one
( e.g. 120 deg and 114 deg ).  Also it appears that the windscreen's center
position with respect to telescope azimuth, differs from the centering
obtained by the alignment clamp.  That is when I've used the alignment
clamp to position the telescope azimuth with respect to the windscreen,
there is a significant jump when the windscreen azimuth servo starts up.
Possibly the zero point of the lvdt needs adjusting?
   Telescope status is similar to last night.  End of night telescope
status was with no instrument mounted,turnbuckled to the windscreen,
counterweights fully down, and the primary covered with Tyvek, enclosure
off.
                                  Dan