Re: Mark IV Cover

[<aah@nofs.navy.mil>]

Tom,
  This cover was an experiment with the basic concept to make
it as light as possible so that a single observer can open/shut.
As with most first tries, this one is doomed to failure.
The metal roof may be sufficient to protect against snow load,
but I bet the frame can't handle it.  The PVC has little
structural strength and softens with heat; I bet it starts bowing
after a few months in the sun.  It has been on the telescope
for about a month, but long-term stability is certainly questionable.
  Blowing snow is very uncommon here, and the frame fits reasonably
tightly on the top of the pier, so I am not concerned about that.
I'll live with this first version through the Fall and then make
modifications or a new frame before winter sets in.
  I didn't send the pix directly to Michael for two reasons:  he
can download them just as easily from my ftp site, and I was
hoping to create a short TN when I get a couple of projects completed
and would need to supply text to him.  Therefore, this is just an interim
report.
  I'm using the aperture masks as crude lens caps since they only
have about a one-inch opening.  That seems to be working for the time
being.  I'd suggest if you are getting lens caps made that you
consider making either a second set with holes as aperture masks,
or combining the two into a cap with a hole and a removable central
portion.  It is nice to be able to reach 4mag brighter for some
projects.
Arne