Integrating light frames taken at different temperatures

[de0s]

Hello fellow stargazers,

I have two sets of data for the same object (a panel of a mosaic I'm currently working on) taken on different nights. The first one is at 0°C, the second one at -20°C. For the first set I calibrated the lights with bias, darks and flats, for the second only with bias and flats.

The thing I'm concerned and I don't know how to proceed with, is that after calibration if I stretch the two images with the same curve, the result is quite different (see attachment).

Now I'm wondering if I should linear fit them before integration... Any thoughts?

Thanks,

Andrei

[de0s]

I tried integrating both sets of data as they were after calibration and compared the result to the integration of only the first set. So, on the image below I have:

- on the left, the integration of 10 calibrated light frames taken at 0°C

- on the right, the integration of 20 calibrated light frames (10 @ 0°C and 10 @ -20°C)

As you can see, the histograms are positioned quite differently. If I leave the mosaic panel as is on the right, I think this will create some problems when I stitch it together with the other panels taken at 0°C. Right?

What do you suggest would be the best way to proceed?