Date: Wed, 2 Jun 1999 04:32:16 -0600
From: long@apo.nmsu.edu (Dan Long)
Subject:  2.5m obslog 990601 ( MJD 51331 )
                           TUESDAY JUNE 1, 1999
                     APACHE POINT OBSERVATORY SDSS 2.5m
                              OBSERVING  LOG
    Observering team:   Dan Long                (APO)
   On the agenda tonight were guiding tests, and a pointing model.  Clouds
prevented either from getting accomplished.  The telescope was open between
about 01:00 and 03:00 during a period of relatively little cloudiness.  By
the time the cartridge was swapped for the engineering camera and the
telescope setup, clouds rolled back in.  After about an hour it was clear
that they were only getting thicker, and I couldn't see FK5 stars with the
EC, so I closed.  I did not reopen.
   Earlier in the night, I had some trouble moving altitude.  While
cleaning drive surfaces, I decided to move down a little in altitude using
the Menu.  When I initiated a move the altitude would move as fast as it
could in the direction I requested.  I noticed that the encoder position
was not changing even though the axis moved.  A check of the cabling showed
a complete path from the encoder to the interlocks rack downstairs.  I did
see however that the number 2 alt encoder was plugged into the number 1 alt
encoder spot ( J-E3 ).  To make a long story short, I eventually got a hold
of Claudio, and he helped diagnose the problem.  The connection path is
correct for the encoder.  It turned out to be a wiring problem within the
interlocks cabinet.  One of the pair of wires inserted into the number 1
position on the number eight interface block had come loose.  Once both of
the wires were in place, the altitude behaved properly.
   When I finally opened, I made the switch to the engineering camera.
Matt Newcomb lent a hand for the swap.  The balance for the EC was 288 on
the counterweights.
  I checked the linear gauges before opening and after heading to the
zenith and relaxing
                                Mirror Numbers
  Primary numbers:
   setmir:  0   3.9   -2.3   -128   -214
   galil:   4350 -1750   0 16300  -11550  -11450
                    before relax        after
   linear gauges:  1:+01.9330           1.9325
                   2:+00.5550           0.5560
                   3:+00.5565           0.5580
                   4:+00.4220           0.4220
                   5:+01.8840           1.8850
                   6:+00.3840           0.3840
   Secondary numbers:
   setmir:  0.0, -236.8, -100.0, -50.0, 348.8
    galil:  44041.,-215019.,169751.,-29125.,-34720.
   I heard a sound while relaxing the primary tonight, that I don't recall
hearing before.  It is a faint scraping sound coming intermittently from
the mirror cell as the mirror was moved by the relax command.  If indeed
the primary is rubbing against something, it should be investigated as soon
as possible.
   The telescope was slewed around briefly.  I couldn't see any stars with
the EC, so I decided to close.
                                WEATHER
   Weather tonight started mostly cloudy.  It remained that way most of the
night, with a spell of partly cloudy between about 01:00 and 02:30.  Winds
were light southwesterly, temperatures were around 12 C, the dewpoint
depression varied between 21 and 24 C.
                                  Dan