[Aavso-photometry] CCD Linearity testing

[Tom Krajci]

From: chemist9755 at gmail.com
> Wouldn't it simply be easier to use a known star field at meridian and  
> take a time series of star  images then do regression for time series  
> and magnitude series using a b filter
> This is the approach I am taking then I don't have to worry about abs  
> lumenosity etc just correct for airmass and bolometric magnitude
> Or is there flaws in this simple measue
>   
That is field testing.  You are at the mercy of weather and it's hard to 
control the maximum pixel value in your exposures, because of:
- wind
- changing seeing
- guiding/tracking errors
- focus shift over time
- optics shift/flop over time
- etc.....

And, you only are measuring the performance of a few pixels in a star image.

I want to precisely control the amount of light that goes to all 
pixels.  Bench testing is much easier than field testing in this 
regard....and can be repeated as often as I wish.  With field testing 
you must wait for another clear night.

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Tom Krajci
Cloudcroft, New Mexico
http://picasaweb.google.com/tom.krajci

Center for Backyard Astrophysics (CBA)
http://cbastro.org/ CBA New Mexico

American Association of Variable Star
Observers (AAVSO): KTC http://www.aavso.org/
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