Re: [ATM] [atm_free] RE: data and musings on thin mirror

["Mel Bartels" <mbartels@bbastrodesigns.com>]

> I could be wrong, but I think my analysis is correct.  This is an
> interesting disagreement, because I think it is one that we can prove
> one way of the other by example, theory, or both.  It's possible that
> we are not yet talking about the same thing, so  we should nail this
> down, first.


I suppose I have as much Ronchi experience as anyone having used it
extensively for 25 years and taught classes with it.  Visually even from an
experienced practitioner's view, I cannot deduce the RC without moving the
Ronchi grating.  

It's not the spacing that matters as much as the shape or the spacing up and
down the bands.  I've run extensive simulations and concluded that the range
of RC values that would fit what can be observed in the band spacing and
their shapes is too great and thus invalidates this method.  This is from a
visual eye use.

Too me this is analogous to using Hartman without moving the screen and
doing the star test at the scope without being able to move the focuser up
and down.

Mel Bartels


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