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Old 15-03-2015, 05:25 PM
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Shiraz (Ray)
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Join Date: Apr 2010
Location: ardrossan south australia
Posts: 4,822
just did a simple validation test. Used 30 normal subs in one stack and then made another stack by adding 5 more subs of the same target taken with a bit of moonlight present (resulting in a stack of 35 varied subs). The brighter subs had about 4x the sky brightness of the normal subs.
The SNR changed by a factor of ~0.9 with the addition of the bright subs (ie the image was noisier). The model predicted that the SNR should change by X0.89, so I am reasonably happy that the model is OK.

In essence adding the 5 bright subs to the good stack of 30 gave about the same result as I would have got by reducing the good stack to 25. It really is not very efficient to add noisy data to good data.

Last edited by Shiraz; 16-03-2015 at 05:51 AM.
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