Date: Mon, 6 Sep 1999 05:51:50 -0600
From: Dan Long
Subject: 2.5m obslog 990905 ( MJD 51428 )
                           SUNDAY SEPTEMBER 5, 1999
                      APACHE POINT OBSERVATORY SDSS 2.5m
                               OBSERVING  LOG
     Observering team:   Dan Long                (APO)
			Stephanie Snedden	(APO)
			Jim Annis		(FNAL)
                         Francisco Castander     (UC)
                         David Schlegel          (PU)
			Bob Nichol		(CMU)
    Tonight the engineering camera was again on the telescope.  The
plan was to check last night's collimation of the primary, get a
small pointing model, then put on the imaging camera and take some
equatorial and off equatorial scans.
    Clouds and nearby storms prevented us opening the first half of
the night, and high humidity took over once the skies cleared some.
We did not open tonight.
    French took a look at the primary support system today, and found
that the main regulator feeding it was set to only about 42 PSI.  He
increased it to between 50 and 60 PSI.  The pressures in the system
returned to normal and the oscillations did not return.  It is odd
that this should have been the case since that regulator is in a
rather inaccessible location in the cone, and probably hasn't been
changed in a long time.
    Engcam without spectroscopic corrector counterweight position was
about 170.  This number was generated with both spectrograph dewars
full.  This was different enough from last nights 115, that the
amplifiers tripped due to the telescope being bottom heavy before we
rebalanced.  With some 25 counts difference per 10 L dewar, the range
of all four being empty to being full ( when imager is on as well ),
is probably going to be too much for the current trip level of the
altitude motors.  How much can the current/torque limit be increased
before we risk slipping?
    Steph and I attempted to reduce the leak coming from the north
side of the dog house door air supply.  The manifold neatly hidden
behind the side panel of the door has developed a significant leak.
We managed to reduce it, but I afraid the manifold will need to be
removed from its current location to fix the leak properly.
                                 MIRROR NUMBERS
    Primary:
    setmir:  0  -15.6   15.6   854   854
    galil:   5650, -3400,  400,  800,  21850,  21250
    linear gauges
  1 = 1.9290
  2 = 0.5595
  3 = 0.5560
  5 = 1.9245
  6 = 0.4255
  4 = 4.0630
  7 = -3.0420
  8 = 3.5440
    Secondary:    Engcam as instrument
       SecOrient: NA
       galil:  -3058550, -2973800, -3038200,  9900,  11500
    TPM data was logged for most of the night using the "start
data990905" command.
    Nitrogen notes:  Both spectrographs were filled between 20:00 and
20:30 and again at about 05:00.  The 180 L dewar for the imager was
changed at about 04:30.
                                 WEATHER
    Weather tonight was mostly cloudy with storms to the south and
west until around 23:00.  Skies became mostly clear to partly cloudy
after that, but the humidity rose too high.  Winds were out of the
east all night. Temperatures were in the lower 50s most of the night.
When DIMM was open it reported seeing from as good as 1.4 to as bad
as 3.5 arcseconds with the mean somewhere around 2.2
                                   Dan