Re: TASS Camera view of M31, etc.

[<aah@nofs.navy.mil>]

I was hoping for something equivalent to the Palomar
Schmidt image of M31.  I guess a factor of 144 less
collecting area makes a difference!
  However, this is *not* the best that I can do with
even the existing images.  I just didn't have time to
stack the 41 2kx2k frames properly, or to add in the
second partial night of data.  I may just junk this
dataset anyway when I finally get the mount aligned
properly and run a proper focus curve.  The mount
is a degree or so off right now, and stars definitely
follow a curved path across the chip.
  Some additional comments on running the system:
I find you need to run the bubbler/dry air system
continuously.  If you turn everything off, the cover
glass will acquire frost/water as the chip is still
cold and some outside air will leak in.  I usually
leave the bubbler and the liquid circulation pump
running 24hrs.  This helps in keeping things from
freezing anyway.
  I'm currently using 8 gallons of liquid (5 water,
3 antifreeze).  That is sufficient to keep the system
cold.  I bought one of the 15gal rectangular plastic
storage bins and cut a hole in the lid to pass the
pump electric cable and the hoses through.  Seems to
work well.  I had to run vinegar through the system to
clean out the calcium deposits left from Chicago Water,
and left the vinegar in for a few days.  This allowed
the acid to start eating away the rubber on the AC cord;
nothing was harmed, but I discovered the hard way to
do short cleaning cycles!
Arne