Re: [ATM] Re: Newtonian Thermals (was ATM Digest, Vol 20, Issue 26)

[Gary Seronik <gseronik@netway.com>]

Hi Gene:

OPTIXWIZ@aol.com wrote:
> Russell Jocoy's question on whether a fan blowing across the optical face of 
> his telescope's primary mirror would affect image quality at the eyepiece is 
> well taken.
> 
> Also, Mark Holm's advice and references are quite relevant.
> 
> However, Bryan Greer, Alan Adler's sometimes co-investigator, does not seem 
> to grasp the virtually revolutionary significance of Alan Adler's 
> anti-convection cell "forced ventilation."

Having worked closely with both Bryan and Alan in bringing their S&T 
articles to publication, I can assure you that Bryan *fully* grasps the 
significance of Alan's cooling scheme.

Alan is trying to accomplish two things at once:
1.  Cool the mirror to ambient, and
2.  Provide improved views while #1 is being achieved.

The main goal of using a fan (no matter where it's placed) is to get 
(and keep!) the mirror cooled down to the ambient air temperature.  Once 
this is achieved, there will be no thermals to blow out of the way.  By 
blowing air across the face of the mirror, one can accomplish this and 
at the same time improve the view to some extent during the cool-down 
phase.  However, even Alan will tell you that optimal performance 
doesn't occur *until* the mirror is at ambient.

Regards,
Gary Seronik

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