[ATM] Re: Second Thoughts on Mirror Support

[jkoptic at juno.com (Jarvis Krumbein)]

If I remeber correctly, the Magellan mirror is also actively supported
which requires a real connection (positive attachment)  with the mirror
section  being controlled.  Therefore, this is not a valid example.

Jarvis Krumbein

On Sun, 8 Feb 2004 19:28:27 -0600 "Ken Hunter" <kb7h@onemain.com> writes:
> 
> ----- 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
> 
> 
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> 


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