Date: Sun, 13 Sep 1998 05:15:19 -0600
From: long@apo.nmsu.edu (Dan Long)
Subject: Obs notes 980912
                        SATURDAY SEPTEMBER 12, 1998
                     APACHE POINT OBSERVATORY SDSS 2.5m
                              OBSERVING  LOG
   Enclosure rolled off at 18:00.  It was a mostly clear to clear night
with nearly calm winds.  The first night back on the air since the end of
June had its expected glitches, but most of the night was productively
spent imaging Polaris.
   The first thing we did after the building was clear was move the
telescope in altitude via windscreen to about 20 degrees.  At this point
went to computer control but altitude drives had forward and reverse
inhibit lights on, and they would not clear.  We moved the telescope a
little higher with the windscreen and then went again to computer control
and this time all inhibits were gone.
   Gain on windscreen alt was set to 2 which made it very sluggish to the
point where is wouldn't follow the telescope reliably in moderate slewing.
We tried putting it back to 7 where it was during the June dark run.  It
worked for a while, but then in a slew back down to around 30 degrees it
began violent oscillations.  The gain was then backed off to 3, and it
worked after that.
   The temporary fiducials for all three axes were set, though only one at
a time can be used right now due to limiting cabling.
rotator   -117301   when moving in direction of decreasing counts
altitude  4143037   when moving in direction of decreasing counts
azimuth     -9165   when moving in direction of decreasing counts
    "     -124885   when moving in direction of decreasing counts
   We had some trouble with the stow position interlock.  The only way we
could get a permit for altitude motion when the azimuth was out of the stow
position was to hold down the switches indicating stow position.  Note that
the elevation was well above 20 degrees.  In fact it was more that 30.  The
switches remain taped.
   There was some trouble getting the telescope to move down in altitude
below about 25 degrees.  The windscreen bumpers were not hitting the
telescope, and the telescope was well balanced.  In fact I could move it
easily by hand and have the windscreen follow, so it is something of a
mystery why the altitude drives kept giving up.
   We spent most of the night on Polaris.  We were able to track Polaris at
rates of a few counts per second for long periods of time.  The finder
scope is now aligned with the chip on the engineering camera.  Care should
be taken when working around the finderscope not to bump it out of
alignment.
   Several focus sweeps were taken.  Some mirror tilts for both primary and
were tried.  Decent images were obtained, but there is room for
improvement.
   Note:  The turnbuckle is off.
                                   Dan