MDM Trouble Report for 2011 Aug 22

Telescope: 2.4m
Observer(s): Halpern, Schroeder (Columbia U.)
Instrument: OSMOS

Problem(s) Encountered:
The Observatory was a flurry of activity all week
as well as the weekend preceding the start of observing,
as the staff tried to recover from multiple damage
by recent lightning activity.

By about 9:00pm the sky had largely cleared, and
we opened up.  The telescope and hiltner computer
experienced many problems, several of which are
new to these observers.  These issues occurred
serially and in parallel, and more than occupied
our time for the entire night.

1. The auto-dome function behaves as if it is
incorrectly wired.  When the auto-dome toggle
switch on the TCS Switch Panel is in the ON
position, the dome does NOT follow the telescope
because the dome error is calculated with respect
to the home position rather than the telescope position.
That is, the dome azimuth just stays at 320 degrees
because it thinks it belongs there.  But when the toggle
switch is set to auto-dome OFF, the dome error is correctly
displayed with respect to the telescope.  However,
the dome will still not follow the telescope, because
now auto-dome is OFF.  So the dome has to be moved
manually to observe, which is very tedious since the
tolerance is so small.  We could not fix this problem.

2. The declination encoder is flaky.  It behaved
similarly as for the previous observer in July,
when Bob had to replace the encoder.  At the beginning
of the night it wasn't encoding.  We tried many 
times to give it a chance to work, and almost gave up
observing.  But after many attempts, the dec encoder 
finally started working.  Of course, the pointing
was lost.  But at least the encoder then seemed to work
for the rest of the night.

(In the process of diagnosing problems 1 and 2,
we restarted the TCS program a couple of times,
and rebooted the TCS computer once, but this did
not seem to be relevant.)

3.  At one point, the images started to be trailed in
the declination direction even though the telescope
was tracking perfectly according to the TCS monitor.
We are sure the telescope was moving in declination 
because the star trails were vertical, and crossed the
boundaries between the CCD quadrants. Once again, 
pointing was lost.  By time we realized what was
happening the telescope was off by several degrees
in declination.

4.  The hiltner computer is flaky.  At the beginning
of the night it was claiming that the data disk /dev/md3
was full, and it didn't allow the Caliban to write any files.
After we deleted all of the old data files on the
disk, a 'df' command still indicated that the disk
was full (0 available bytes).  This seems ominous.
We rebooted hiltner, but the login stalled at the end of
the countdown to begin windows.  We rebooted a second time,
and this time the login was successful and 'df' was correctly
listing the amount of available space.  In retrospect,
I remember seeing hiltner stalled at the same stage on Sunday
when we arrived at the Observatory, and I had to reboot
it then as well.  This is definitely a problem with hiltner,
and not the instrument, nor the IC, nor Caliban.

5.  The motor mike was way out of focus.  With OSMOS on, it
is more difficult to get access to and move it.  Furthermore,
the fine guider focus mechanism does not appear to be moving,
so it is really not possible to focus the guide star by any
method.  It's a small donut at the moment.  We're doing imaging,
not spectroscopy, and it is evident that the guiding is
unacceptable.


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Submitted on 2011 Aug 23 [5:23:01]