Date: Fri, 21 May 1999 06:02:17 -0600 (MDT)
From: hayes@apo.nmsu.edu
Subject: 2.5 m obslog 990520 (MJD 51319)
			Thusday May 20, 1999
		Apache Point Observatory SDSS 2.5m
			     Observing Log
Observing Team:
		Jeffrey Hayes (APO)
		Ellyne Kinney (APO)
		Don Holmgren (FNAL)
                Bob Nichol (CMU)
                Jim Annis (FNAL)
		Russell Owen (UW)
                Connie Rockosi (UC)
Weather:  Clear with low dust.  Windy: ~10 mph steady and gusts
up to 20 mph.
On tonight's menu, we refined the pointing model from last night and
put the autofills on the spectrographs to test for flexture.
We opened at 8:30 pm MDT.
We did obtain e-mail from Dan Long and Russell Owen
indicating that for a good pointing model we should do an axis init
between each star pointed to, and that there is a modified instrument
block for the engineering camera that has the movement of the rotator
in it, and that too, should be used.  Both of these suggestions are taken
up for tonight.
We opened at 8:30, but found the telescope to be out of balance.  We found
the correct CW positions to be 203 not 165.
We started the night by slewing to Arctrus (213.90958,19.185) to check the
pointing, focus and instrument block.  The offset we needed to center the star
was -.07, 0.01.  The focus would not change when we first tried to reset the
value.  We talked to Craig and Russell about this and they were able to fix
the problem by stopping and restarting collimation.  The focus for the star
seemed to be really off, we were getting doughnuts for the image.  After
fiddling with the focus, we settled on -400.  The image was saturated even
after a .1sec exposure so this was not a good star for fine tweaking the
focus or testing the centering for the pointing model data.
The star was found using the engineering camera, and
centred the star on the CCD.  Once that happened, I centred the star in
the finder telescope (a small adjustment in AZ was needed).
We slewed to FK5 star that was ~4mag (228.79733,4.9393611).  The offset needed
to center this star was -003, 0.01.  The focus was really bad, (a doughnut
again), so we took the telescope to 0,87 Az, Alt to home the primary and
secondary.  We then went back to the previous star and focused.  The final
value was -900.
Russell then tested to make sure DOPTERRKLUDGE would center the star properly
in the chip.  It worked as he expected.  We then went on to take the pointing
model data.  We needed to use the finder scope to center 4 of the 12 data
point and notice that the focus was off again, (we were getting doughnuts).
We refocused to the value -750 (at star 7 in the data set).
Once the data were taken, Russell fit the data and found errors of 3" rms
with an 8 co-efficient model.  We planed to slew to to 3-4 star to check the
new pointing model and to use them to add to the pointing model.  Unfortunately
the MCP crashed during the slew. (2am) We got the error message:
"Target is moving too fast: telescope cannot aquire it".  We needed to reboot
and reset the fiducials.  With the new fiducials it would not be possible to
add the new points to the current pointing model data set.
The MCP error message was:
"axis 0 not running: state=e".
(NB -- See the separate e-mail from Owen outlining the pointing model.)
Near 3 am, we changed to the mosaic camera.  We had an ALT axis runaway just
after we tried to pin the telescope at the instrument change position.  A crash
happened, but an Amp reset cleared up the problem.  Note that
the pin position for instrument change (i.e. the locking pin) is at
89d 46' 50" (more of this later).  We also note that during the change,
we had to push the telescope slightly in order for the rails of the
mosaic camera's cart to be lined-up properly.  However, we (Connie and I)
managed to move the telescope in AZ by 25 degrees while the doghouse door
was open.  This necessitated a slew back to the stow position.  We also had
considerable trouble getting the saddle latches to engage: latch 2 would work
fine, but latch 1 would not engage.  Finally, Connie used the hydraulic lift
to lift the camera at the same time that I engaged the latches.  This worked
but is obviously not an appropriate method.  Note that the ALT position for
instrument change must be 89d 50' 40" (this was the MCP position after
the saddle latches caught).  We must have the pin position and the
instrument change positions agree to better than the numbers quoted herein.
Using the mosaic camera, we had only time enough for a bit of imaging data.
Data was taken on the equator, at the meridian and rotator = 89.89d The
focus positions were 0, 150, 450, -150, -250, 100.  Before we closed, we
homed the secondary: the errors were 10k 0 0 250 50.
For the record, the CW positions for the camera, 1 spectrograph, and stuff was
700, for decent balance.
We also record the opening and closing before and after MCP fiducial readings:
Opening:
AZ 122:59:59:992 (before fiducial set)
   122:59:59:852 (after  "  )
ALT 11:59:59:999 (before fiducial set)
    11:59:51:650 (after  "  )
Rot 02:59:59:994 (before fiducial set)
    02:59:43:506 (after  "  )
Closing:
AZ 121:59:59:982 (before fiducial set)
   122:00:01:005 (after  "  )
ALT 7:59:59:899 (before fiducial set)
    8:09:02:279 (after  "  )
Rot 01:59:56:891 (before fiducial set)
    02:00:11:087 (after  "  )
One last thing; while slewing from the meridian to the stow position, (a move
of 120d), the telescope stopped at ~ 42d.  A re-issue of the move command
sent it on its way again, but there was no indication of why this should
have happened.  (I was using the MCP at this point.)
We closed at 5:40 am
Ellyne and Jeffrey