Date: Sun, 15 Nov 1998 05:58:33 -0700
From: long@apo.nmsu.edu (Dan Long)
Subject: 2.5m obslog 981114
                        SATURDAY NOVEMBER 14, 1998
                     APACHE POINT OBSERVATORY SDSS 2.5m
                              OBSERVING  LOG
   Tonight was highlighted by finding the best primary position values to
date and getting the best images yet ( many chips less than 1.0 arcsecond
fwhm )!
   The telescope was opened tonight at about 17:00.  During twilight, Steve
Bastian took some measurements of the mounting blocks for the tape encoder
system.
   The building clear switch was disconnected during the day in preparation
for modifying it to sense the building over a longer distance.  This means
that the building clear interlock must be bypassed in both altitude and
azimuth to operate.
   The first half of the night was spent taking data on the southern
equatorial stripe.  Seeing during this time was around 1.5 arcseconds.
   Shortly after midnight the power supply to dewar 4 failed, and was
swapped out for a new one.
   We continued parked on the equator at the meridian, and took data after
Connie made some changes to the ccd parameters to increase full well depth.
During run 242 we crossed a nice nebula in Orion ( centered on frame 98 ).
   The last two hours of the night were spent adjusting optics as the
seeing had improved substantially.  After noticing that the numbers we had
been using for the primary were not collimated numbers ( tilts and
translations in proper proportion ), it was decided to start from scratch.
Since the seeing was good and the mirror was well equilibrated, we quickly
found new parameters.  They are as follows.
        setmir     0   -4   20   1070   210
        galil   4850  -4450   1000  -8300  25700  25700
These values gave nice looking images over the whole array.  In fact we got
some frames where the worst fwhm was less than 1.3, and several chips were
less than .9 arcseconds!  We're keeping our fingers crossed that the
weather and the mirror support stay unchanged for tomorrow night.
                                Dan