Date: Sat, 19 Sep 1998 06:41:38 -0600
From: long@apo.nmsu.edu (Dan Long)
Subject: 2.5m obslog 980918
                         FRIDAY SEPTEMBER 18, 1998
                     APACHE POINT OBSERVATORY SDSS 2.5m
                              OBSERVING  LOG
   The enclosure was rolled off at about 19:20 to mostly clear skies.
Skies became clear by astronomical twilight and remained so until dawn.
Seeing was very good tonight.  The 3.5m reported fwhm from .8 to 1.0
arcseconds in R.  Preliminary looks at imager data showed fwhm around 1.2
arcseconds for the strip.
   We set up and parked on the equator at the meridian.  Some testing of
focus routines were done.  Next we moved 8 arcminutes north and took a
northern strip of equatorial data.  This ran from about 23:30 until shortly
after 05:00.  Coordinates were
                AZ:  000:00:01
                EL:  057:27:52
               ROT:  089:50:36
   These coordinates were referenced to fiducials for each axis.  The
positions declared for the fiducials were
                AZ:  120:49:20
                EL:   17:07:00
               ROT:    0:00:00
   The last part of the night was devoted to taking a focus sweep and then
adjusting primary parameters, trying the new idea of relaxing the
transverse supports by going an extra bit forward then back in piston after
each down command.  The result was beautifully symmetric donuts, and in
focus fwhm of .94 arcseconds!!  Jim Gunn will have recalculated tilts and
translations for tomorrow night's run.  Just for the record the primary
parameters ( in setmir terms ) which yielded such nice images were
              0 15 0 -1270 0
At the time the secondary was at
              1100  -217  0 0 112
   Tonight we had trouble moving the altitude axis on two occasions.  The
first instance was when trying to move at the newly allowed higher rate.
It would stop when 190000 counts per second were requested.  It was
repeatable and was not running into the windscreen.  The second instance
was after being parked for a couple hours.  After being unable to move the
axis, I went to the telescope and found both altitude amplifiers with the
LEDs set which would be set when a stop button was in.  However no stop
buttons had been pressed since the last time the telescope was moved, and
all other amplifiers were still showing all green LEDs.  The amplifiers
were cleared by pressing the reset buttons and I was then able to move the
telescope.
                                   Dan