Dec Drive, etc.

[<aah@nofs.navy.mil>]

The reason Tom keeps bringing up the subject of the
Declination Drive with my name attached is that he and
I are running the Mark IV in different modes.  Instead
of just repeat scanning of a single declination zone, I tend
to move all over the sky.  For example, here is what I am
programming ARNE to do automatically this evening:
    * turn on TEC cooling, move to RA/Dec limits
    * when dark, take series of 90 second darks.
    * at 0300 UT, move to BP Vul and take 90-second exposures
      for 2.5hrs.
    * when finished, take series of 90 second darks. (I don't
      want interspersed darks during the BP Vul dataset because
      the time series needs to be continuous.)
    * go into survey mode: single RA, 150 second exposures moving
      about 3.5 degrees in declination between exposures for about
      8-10 moves; then move to new RA, move back to the starting
      declination and repeating for the rest of the night. Darks
      are interspersed, taken just before moving to the next RA.
    * when finished, park the telescope and turn off TEC.
The RA drive moves nicely and I have no problems with it.  The
Dec drive depends on the Dec clamp, and that is where most of
the repair activity is taking place.  I think it is working
well enough to give the full schedule a shot.
  The CCD and electronics are working really well.  I'm impressed
with what Tom got from Loral for $1700.  Reading out two CCDs of
this size in 48 seconds is faster than what we do with our
scientific systems, and there is no obvious pattern noise.
The image quality looks good, but I'm sure I'm not at the
best focus yet.  Several problems still remain that I'm not
sure I will have time to address before Europe; fixing these
will make the difference between 0.03mag errors and 0.01mag errors,
or in going another magnitude fainter.  The system works as-is,
but I want it better!
Arne