Re: [ATM] first light on a Lurie-Houghton

["vladimir sacek" <vla@toast.net>]

Guy Brandenburg wrote:

> I could tell that the corrector plates were not truly parallel to the 
> primary, but didn't have the means to fix and adjust that at the time.

The only thing about Houghton corrector that has very tight tolerances is 
its tilt. It is roughly ten times as sensitive to it as Schmidt corrector, 
whose wavefront error in terms of the tilt angle t (in radians) is given by 
W=tD/48F^3, D being the aperture diameter and F the mirror focal ratio 
number.

As little as 1/10 degree tilt would produce some 0.6 wave of centerfield 
coma (equivalent to somewhat over 1/3 wave of spherical aberration).

Vlad 

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