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Help with CCD flats
Been experimenting taking CCD flats and have been very frustrated.
My old image of NGC 2070 without flats clearly shows gradient (photo 1), but when I applied my flats, it made it worse (photo 2)
When I examined my flats, I think I found the issue, only the first flat had a pixel value of 10.5k average (photo 3), but all other flats (I took 35 of them), showed pixel values of 31.3k (photo 4) average, even though the parameters were the same!
So the questions I have are:
1. Is a flat with average pixel value of 10.5k acceptable? (I am using QHY8, using white t shirt over computer screen).
2. Why do the values change for all other flats even though I took them with same settings?
3. What else am I doing wrong?
Thanks
Bo
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