[ATM] ATM edge support

["The Alarm Co." <tac@i1.net>]

I just toured the McDonald Observatory (part of the Texas Star Party
festivities) and got a good look at the back end of the 107" scope.  It has
an astatic cell with about 30 points (the guide wasn't sure of the exact
number) that looked pretty ordinary.  Here's the interesting thing:  the
edge supports are also astatic.  It looked like there were about 10 points.
Since it's on a equatorial mount,  the astatic design should automatically
compensate for the variable orientation of "down".  Sounds like a viable
alternative for those who don't want to glue their mirrors in or resort to
multiple slings.
I also toured the Hobby-Eberle.  Here's a puzzle (one the guide couldn't
answer).  Its primary is an 11 meter f/1.5 sphere.  How much difference in
sagitta would there be if it were a paraboloid? (answer withheld as an
exercise for the reader, and also because I haven't figured it out yet)

 *  Best regards, Bob
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