Quote:
Originally Posted by gregbradley
How do you find out you have negative values?
Greg.
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I just open the dark in CCDStack., select all of the image, and the info box pops up. It's right there as a min value.
After the comment of Stan that a bias (as a dark) or a dark is required to properly subtract a flat I'm wondering how you are successful. Perhaps yours looks OK because you have a lot of signal. The image I've been unsuccessful with is an OIII with low signal. As I've said it flats fine with a dark....
Have you tried to make a pix map yet? It's pretty cool to see it work. I used a dark frame and did a hot pix rejection. It grabbed all the pix and turned them red. They really stand out against the dark. That gives you the map. Just for fun I used the dark to try interpolation. Like magic they were history and my dark looked a lot like a bias frame..
Peter