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Critical warning: flat-field calibration can not be performed - but why?

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(@crw4096)
Molecular Cloud
Joined: 6 years ago
Posts: 3
Topic starter  

Hi all,

I'm trying to run APP to do calibration etc. all the way to integration. At any rate, in the calibration step, I get this "critical warning" (see below).

APP message

 I have a set of dark frames, bias frames and flats that are all taken at the same gain and offset, and they're all with the same camera and hence same dimensions.

Why am I getting this message? The only thing I can guess is that APP wants Dark Flats, which I am not willing to provide, since that requires collecting a bunch of dark frames at the same exposure as the flats, which happen to be algorithmically determined. Also, the exposure time is so short I do not believe dark frames are required (less than 5 sec). And even if someone else believes dark frames are required, I ought to be able to override this and use the flat frames I have collected. I've been doing things this way for multiple years and I'm not sure why this is suddenly happening now.

Instead of using the "incorrect" bias or darks, I get "calibrated" images that are not calibrated at all. Is there a way around this? Also, do I seriously need Dark Flats? Is this a FITS keyword problem?

Thanks for your help,

Charles



   
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(@imnewhere)
Black Hole
Joined: 9 years ago
Posts: 174
 

I've only used dark flats if using a dedicated astro camera, and I don't use both bias and dark flats at the same time. Have you looked at your fits header to see if there is anything weird, like if your bias aren't actually marked as bias and so the master bias isn't built?



   
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(@crw4096)
Molecular Cloud
Joined: 6 years ago
Posts: 3
Topic starter  

Figured it out - I have two ways of taking flats depending on the telescope I'm using. In one case, it's just the normal image capture SW set to mark the images as "flats". Processing works "just fine". In the other case, I'm running a Python script that I thought was doing the same thing, but it's not: it is capturing a slightly different image size! Had to really squint to see that. Now, to figure out why this is happening, because it never happened before when I was using a different camera...

Thanks for your thoughts,

Charles Wright



   
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