Date: Sat, 1 May 1999 05:43:19 -0600
From: long@apo.nmsu.edu (Dan Long)
Subject: 2.5m obslog 990430 ( MJD 51299 )
                           FRIDAY APRIL 30, 1999
                     APACHE POINT OBSERVATORY SDSS 2.5m
                              OBSERVING  LOG
   The fiber cartridge and corrector are on the telescope, as well as the
guider electronics box.  Tonight's goal was to get light down the fibers
and work on the instrument block.  We got starlight, and collected some
data which hopefully can be used to generate the instrument block.
   The first thing we found was that the instrument block for the
engineering camera had a rotation 180 degrees off from what the cartridge
needed.  So I created an instrument block called SPECTRO which had
rot_inst_ang 180 degrees from that for the engineering camera.
   We tried slewing to field containing guide stars, and could not see
anything.  We then decided to go to Vega and place it on two of the fiber
positions.  We found the star after a little offsetting.  We also found the
focus was around +3400, which explains in part why we could never see the
14th and 15th magnitude guide stars with the focus anywhere between +/-
2000.
   We collected data which I hope will allow the generation of an
instrument block for the guider.  I started by slewing to Vega, which
should put it at the boresight.  Coordinates are 279.1883, 38.7783
fk5=1993.5.  All data were collected with rotator at 0 object using the
SPECTRO instrument block.
   The first fiber position is offset from the boresight by -0.27713,
-0.10787 degrees on the sky.  I slewed the telescope to 279.4845, 38.8862
fk5=1993.5 in order to put Vega down that fiber.  It took object offsets of
.0525, -.009 to center it on the fiber.  The resulting position is
279.5370, 38.8772 fk5=1993.5.
   The second fiber position is offset from the boresight by 0.18376,
.40000 degrees on the sky.  I slewed the telescope to 279.0045, 38.3783
fk5=1993.5, and had to offset by -.0820, .0055 object to center Vega.  The
resulting position is 278.9225, 38.3838 fk5=1993.5.
   Russell, do you think it is possible to take this data and back out the
translation, rotation, and scale for the instrument block?  It seems that
with two points one should be able to at least determine the boresight
offset and rotation.
   Note that once tonight the MCP hung while moving the rotator.  I could
not get ctrl-x to reboot, so the reset button was pushed.
   The rotator fiducial is still wrong, so we set the rotator zero by
aligning the pointer and mark on the back of the telescope.
   The wider azimuth stow angle sure is nice.  It made putting the
telescope away much easier.  Thanks Glenn et al.
   One final note is that we tracked Vega for nearly an hour at one of the
fiber positions, and noticed only a slight drift.  This should easily be
taken out by guiding once a proper instrument block is generated.
                                  Dan