[Aavso-photometry] Errors on AIP

[Michael Koppelman]

For the SNR, yes, I believe this to be true. The "total" error (total 
in quotes because I doubt there is such thing) the comp star sigma 
generally dominates. Currently AIP users can use the K-C standard 
deviation as their error and get most of the way there. However when 
the comp stars are brighter than the target, one should really factor 
in the shot noise as well.

One other note: AIP has a way to figure out your gain and readnoise 
that is very quick and easy. It's under the "Measure" menu and is 
called "Characterize CCD Camera". My spreadsheet requires this info to 
be accurate.

Latest version of the spreadsheet is here:

http://www.lolife.com/astronomy/AIP_Err.xls

Michael


On Jul 15, 2004, at 6:50 AM, Radu Corlan wrote:

> One important thing to note is that in most cases, if the sky is not
> _very_ bright and the aperture is not too large, photon shot noise
> dominates by a good margin.