[ATM] Re: Second Thoughts on Mirror Support

[kb7h at onemain.com (Ken Hunter)]

----- Original Message ----- 
From: "Stuart Hutchins" <stuart452@earthlink.net>

> Any sort of  "positive attachment" violates the fundamental requirement of
> "flotation".  That 's why you hear all the howling when you say RTV.  No
> professional grade instrument with a solid mirror uses glue to hold it down.
> 

Hmm...

Better tell that to the Mirror Lab folks at the University of Arizona... they're
using RTV to hold the 8.4 METER Magellan mirror to the loadspreaders and
I'd surmise that the Magellan is a "professional grade instrument"

http://medusa.as.arizona.edu/mlab/lbtcast.html

Additionally, many observatories are using RTV to hold fairly large secondary
mirrors to their supports.

All this "chit-chat" on what's possible and what's doable fails to take into
account that the average seeing conditions are going to be several magnitudes
worse than the deflections seen (or computed and not seen) in these scopes.

I agree that one should make their scope to the best of their ability but now
that we have computers to tell us what we've been doing for so long is not
going to work now... maybe we should give up making telescopes and move
on to becoming the servant of our computers and all those small numbers that
don't mean anything in real life.

What do you want to do, build a scope or worry about tiny nonsensical numbers?

Ken Hunter