Thanks,

Unfortunately, I was not wise enough to acquire those frames during my last night session, and it looks like it will not be possible for a while. However, I made the following experiment this afternoon: I connected my ST10, cooled it to -12°C, and acquired with Ekos:
- a frame of the guide chip, without subtracting a dark (case "dark" unchecked): light2s_green_nodarksub.fits
- a dark frame: dark_2s_green_guide.fits
- a frame with "dark" checked: light2s_green_darksub.fits
The files can be retrieved here: pfilliatre.free.fr/indiforum.zip
As the name implies, the exposure is 2s, with a green filter. Of course the only thing that can be seen is the ambiant light, however there is something interesting: the frames with and without dark subtraction are very similar. Indeed, if I subtract the latter with the former, the result is not similar to the dark frame, as it should be, but to random noise. It looks like the dark subtraction is not done, which could explain the very noisy aspect I observed when aiming at a mag 9 star. The dark frame by itself looks correct.
Any idea ?

Philippe

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