Date: Tue, 9 Mar 1999 23:41:21 -0700
From: long@apo.nmsu.edu (Dan Long)
Subject: 2.5m obslog 990309
                           TUESDAY MARCH 9, 1999
                     APACHE POINT OBSERVATORY SDSS 2.5m
                              OBSERVING  LOG
   Tonight I observed the inside of the telescope with the engineering
camera. Several dozen frames were obtained at various exposure times and
lighting conditions and at three different positions with respect to the
optical axis.
   Two things to note.  The fibers were found to be flakey leading from the
engineering camera.  The fiber is labeled data 1.  I switched it out with
the pair labeled "rotator ethernet", and had no further camera
communications troubles.
   The second thing occured while I was setting the counterweights for the
engineering camera.  When the switch was set to move the number 2 weight,
the number 4 weight moved.  Switching to the number 4 weight also moved the
number 4 weight.  Power cycling the controller unit restored normal
operation.
   A 4.2mm lens was placed on the engineering camera and set at about f/11.
The first lighting setup was to have the incandescent and arc lamps on
with the telescope at about 6 degrees.   The access panels were put in
place around the camera and the space between the camera and the rotator
was covered ( what else.... duct tape :).
   Due to the comminucation problems I was having with the camera, I first
took a data set using the photometrics software, which inferred by the
extension given to the default file name, saved in fits format.  Another
set was taken with the IPlab software when the fiber was replaced.  Finally
a third set was taken with lighting set up to only come from the front of
the telescope.  This avoids having significant light come in from the back
around the corners of the windscreen.
   A first examination of the data shows that as one goes off axis, one can
see the windscreen inner wall from between the conical and primary baffles.
This appears to be the only significant source of light outside the pupil.
   The files are all on galileo in the ftp directory /pub/images and
accessible via anonymous ftp.
The files are listed as follows.
Files                             exp     gain    position from axis ( galil)
Photometrics Data - incand & arc lights:
baffle_04.fits - baffle_13.fits    5 sec    3       0 deg  (-653,000)
baffle_14.fits - baffle_23.fits    5 sec    3      1.0 deg (205898)
baffle_24.fits - baffle_33.fits    5 sec    3      1.5 deg (635346)
IPlab Data - incand & arc lights:
baffle_34.fits - baffle_38.fits    15 sec    3      1.5 deg
baffle_39.fits - baffle_43.fits   1.4 sec    3      1.5 deg
baffle_44.fits - baffle_48.fits   1.4 sec    3      1.0 deg
baffle_49.fits - baffle_53.fits    15 sec    3      1.0 deg
baffle_54.fits - baffle_58.fits    15 sec    3       0  deg
baffle_59.fits - baffle_63.fits   1.4 sec    3       0  deg
IPlab Data - two 300W work lamps placed at either side of telescope near front:
baffle_64.fits - baffle_68.fits  0.15 sec    3       0  deg
baffle_69.fits - baffle_73.fits     3 sec    3       0  deg
baffle_74.fits                     15 sec    3       0  deg
baffle_75.fits - baffle_79.fits  0.14 sec    3      1.0 deg
baffle_80.fits - baffle_84.fits     3 sec    3      1.0 deg
baffle_85.fits - baffle_89.fits  0.14 sec    3      1.5 deg
baffle_90.fits - baffle_94.fits     3 sec    3      1.5 deg
baffle_95.fits                     15 sec    3      1.5 deg
Note:  Image 14 was taken before the galil was finished with its move.
                                Dan