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Re: [APML] RE: September Images

Glenn Ray wrote:
> 
> You also mentioned that you had A3-A4 errors w/ the ST-4.  This would equate
> to 2.0-2.7 arcseconds error (@ 1825 mm) which is borderline acceptable for 
> that focal length.  That may also be a factor. 
> 

A3-A4 is equivalent to 60-80% of one ST-4 pixel (0.013x0.016 mm). Taking
the larger dimension, 0.016 mm at f=1825 corresponds to 1.81 arcseconds.
Hence A3-A4 corresponds to 1.1 - 1.5 arcseconds, which I consider quite
acceptable for that focal length.

Thomas

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