Date: Sat, 20 Mar 1999 06:26:04 -0700
From: long@apo.nmsu.edu (Dan Long)
Subject: 2.5m obslog 990319
                           FRIDAY MARCH 19, 1999
                     APACHE POINT OBSERVATORY SDSS 2.5m
                              OBSERVING  LOG
   The enclosure was opened tonight due to observing!  It was a beautiful
clear night with light winds ranging from north to west.  This made for
very nice seeing the second half of the night.  Several times the seeing
dipped below 1.0 arcsecond, and was usually better than 1.4 arcseconds.
The northern equatorial strip was imaged ( run 745 ) from about 23:00 to
05:00.
   The enclosure was rolled off at around 14:30 this afternoon.  It was not
put back before observing began.  This may explain the strongly astigmatic
images seen the first half of the night when slightly out of focus.
   There were some communication problems with the secondary at the start.
Power cycling the M2 actuator box then homing fixed the problem.  Also the
linear guage readings were enough off that it was decided to relax the
primary.  After the relax the astigmatism was still preset.  A check of out
of focus images at the end of the night showed nice donuts with none of the
nasty astigmatism seen earlier in the night.
  Primary numbers:
   setmir:  0 -25.8  17.2  939  1409
   galil:   6300 -3850 150 9700 24750 24100
                last observing   before relax    after relax
   linear guages:  1:+01.9265    1:+01.9270      1:+01.9265
                   2:+00.5610    2:+00.5615      2:+00.5615
                   3:+00.5565    3:+00.5570      3:+00.5575
                   4:+00.3575    4:+00.3575      4:+00.3565
                   5:+01.9295    5:+01.9270      5:+01.9180
                   6:+00.4300    6:+00.4285      6:+00.4285
   Secondary numbers:
   setmir:  1503*  -255   0   0 133
    galil:  1750167   1830167    2098938   -9642  -16642
       *The piston was taken over by the focus loop and did not remain zero.
   There was a problem with the focus loop tonight.  It seemed to stop
communicating with the tcc.  The window it was running from seemed not to
show any response in the telrun window I had.  In fact it was slowing down
the tcc considerably.  We got out of that session and restarted.  The tcc
was much happier.  Restarting the focus loop showed the expected secondary
move commands.  However the loop seemed to be moving the secondary more
than 100 microns out of focus and was showing no signs of turning around in
5 minutes or so.  It was decided to switch to manual to avoid trashing the
run.  Things were stable enough that we could just set the best focus
piston value and it stayed within 10 counts.
   The enlosure was closed at about 06:00.
                                   Dan
1:+01.9265
2:+00.5615
3:+00.5575
4:+00.3565
5:+01.9280
6:+00.4285