Date: Tue, 23 Mar 1999 07:45:35 -0700
From: long@apo.nmsu.edu (Dan Long)
Subject: obslog 990322 ( MJD 51260 )
                           MONDAY MARCH 22, 1999
                     APACHE POINT OBSERVATORY SDSS 2.5m
                              OBSERVING  LOG
   The fan was turned on at about 16:00.  The enclosure was rolled off at
about 18:15, at which time we set up on the southern strip.
   Tonight was punctuated with tape drive problems.  ID1-1, ID3-2, ID4-1,
ID1-2, ID6-1 all requested cleaning tonight.  The problem with that is that
it apparently brings archiving to a screeching halt, and at least on one
occasion, only recover via a reboot of the stopped node.  The first time (
around 23:15 ) ID1-1 requested a clean, and ID1-2 stopped archiving as
well.  We tried without success to get the tape drives writing again.  A
reboot of ID-1 did fix things.  Connie had some success getting things
going the second time ( about half an hour later and this time ID4
complaining ) without having to reboot.  She is sending out a message on
how she was successful the second time.  Round three was ID1-2 requesting
cleaning.  Just as we managed to get the archiver going again, AD3 and ID1
nodes died.  Two successive reboots could not get ID1 to do more than a
partial frame at the start of a goDrift ( this was later traced to the fact
the pool had filled with all the goings on tonight ).  ID6-1 chimed in for
a cleaning while we were trying to get ID1 node going again.
   The rotator went into oscillation on two occasions tonight.  The first
was as soon as I let out the last stop button.  The oscillation was on the
order of a degree in amplitude, and about 3 Hz in frequency.  I stopped
oscillation by hitting "s" on the Menu.  An amp reset did not stop the
oscillation.
   The second occasion was after I had set up the rotator to a nominal
drift scan position.  I left the rotator in "hold" and when we opened the
shutters to start a drift, the stars all looked like figure 8 patterns
about 10 arcseconds high.  All three axes were in some oscillatory motion,
however alt and az were apparently moving a few arcsecond back and forth in
response to the oscillations in the rotator.  Once again, hitting "s" in
the Menu for the rotator stopped the oscillation.  We ran the rest of the
night with the rotator in the stopped state, once we had it properly
positioned.  No further oscillations were noted.
   The altitude also oscillated again when coming up out of stow position.
I stopped it with "s" in the Menu.  I started the move again with no
oscillation this time.
   Tonight was pretty much a bust for data.  Skies were never clear, and
the second half thick cirrus covered most of the sky.  Seeing was between
1.3 and 2.5 arcseconds.  We set up on the southern strip, and ran from
about 20:30 until 23:00 before all the DA problems.
                                Mirror Numbers
  Primary numbers:
   setmir:  0 -25.8  17.2  939  1409
   galil:   6300 -3850 150 9700 24750 24100
   linear guages:  1:+01.9270
                   2:+00.5610
                   3:+00.5570
                   4:+00.3565
                   5:+01.9295
                   6:+00.4300
   Secondary numbers:
   setmir:  1510*  -255   0   0  133
    galil:  1759000, 1839000, 2107750, -9650, -16650
       *The piston was taken over by the focus loop and did not remain here.
   As this was the last night of the March dark run, at the end of the
night we took the camera off and put it in the dog house.  While lowering
the counterweights there was a problem with the controller.  On
counterweight number 1, down made the weight go up and up made it go down.
When it reached bottom it did not stop, and probably crushed the limit
switch.  Rather than risk any of the others, the remainder were lowered
using a drill motor.  The enlosure was closed at about 07:15.
                                   Dan