[Aavso-photometry] (no subject)

[Michael Koppelman]

Nope, that doesn't work. You are multiplying by a constant so your  
counts go up. If you are not adjusting your gain and readnoise  
headers, you are fooling your software into thinking you have more  
counts than you do and it is hence incorrectly calculating your  
uncertainties.

Cheers,
Michael

On Aug 18, 2005, at 10:19 AM, Keith Graham wrote:

> It is well known that s/n can be improved by stacking images. I was  
> wondering if stacking the same image onto itself would serve the  
> same purpose as stacking several images taken separately. I tried  
> this by saving the same image using different names so I could load  
> them all into my image-processing program and stack them. I did  
> find that my s/n and uncertainty improved immensely. Does anyone  
> know of any reason why I should NOT be doing this to get better  
> photometric measurements on dim variables?  It appears to work just  
> fine, but I could be missing something.
>