No Darks - Hot pixe...
 
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No Darks - Hot pixels not removed


(@midnight_lightning)
Red Giant Customer
Joined: 4 years ago
Posts: 104
Topic starter  

Hi, 

I usually use all calibration frames (Flats, Dark Flats, Darks, Bias) in pre-processing but I have a good CCD and image at -20C so in theory I shouldn't need to use Darks.

So tonight I tried using all of the above except Darks and ended up with hot pixels still showing after Calibration. I was using Average weighting and tried Windsor/Mad/Sigma rejection to no avail.

Then tried again with Darks and hot pixels are gone.

Any thoughts, do I need Darks to get rid of hot pixels?

BTW, I created a bad pixel map and it turned out looking like a grey image without the Darks - with the Darks the hot pixels show up fine. Is that expected?

 


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(@midnight_lightning)
Red Giant Customer
Joined: 4 years ago
Posts: 104
Topic starter  

Any thoughts?


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(@vincent-mod)
Quasar Admin
Joined: 5 years ago
Posts: 4736
 

Apologies, the week has been very busy overhere.

So yes, the purpose of a dark is exactly that, to identify hot pixels. And amp-glow, if that would be the case. You can create a BPM with a proper, long dark and if you have no amp-glow, you can use just a BPM. Having this grey background is normal indeed.


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(@midnight_lightning)
Red Giant Customer
Joined: 4 years ago
Posts: 104
Topic starter  

Thanks Vincent, much appreciated.


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(@vincent-mod)
Quasar Admin
Joined: 5 years ago
Posts: 4736
 

No worries, thanks for your patience. 😉


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