From: "aa27100" <antonio.agnesi@unipv.it>

Date: April 10, 2008 1:50:45 AM MDT

To: Astro_IIDC@yahoogroups.com

Subject: Re: Mathematics of Stacking

I believe that the S/N ratio improves by a factor of 2 to the square  

of the number of frames used, ie: 100 frames stacked would improve the  

S/N over 10 frames by a factor of two - to gain another 2x increase in  

signal quality, 1000 frames would be required.

Alan,

S/N is proportional to the square root of the number of samples, so you actually need 400 

images to improve by a factor 2 the S/N ratio of a 100-frames stack. Anyway, this shows that 

to improve drastically the S/N, say by an order of magnitude (a factor 10), one needs 100 

times more images (or total movie time, or GBytes..).

Cheers,

Antonio

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