Last night the offset (and maybe the gain) suddenly changed on my ZWO ASI 183MM Pro cooled camera.
These are the events that happened:
1. I connected the camera through SharpCap to do a Polar Alignment with the main imaging camera and scope. When complete, I disconnected the camera and closed SharpCap
2. I then connected the camera through APT, using Shift-Connect and set the Gain to 140 and Offset to 20, and began cooling.
3. While cooling I went to connect the ZWO ASI224MC guide camera in PHD2, but accidentally chose the main camera, the ZWO ASI183MM. I disconnected and connected the correct camera, but after that could not get the 183 to work in APT, and tried to disconnect and reconnect, losing cooling, but that did not work.
4. I shut down and restarted APT and reconnected , using the Shift-Connect, set the Gain to 140 and Offset to 20, and began cooling again.
5. Once cooled I began imaging. The images had a larger minimum than I recall for that offset, and previews (using Nebulosity) showed them to be washed out and grainy. But I let it image for over an hour, not sure if this was normal or not.
6. Then, while previewing, after the 12th 5-minute image, subsequent images became completely different. The offset had dropped back down to "normal", and the mean was nearly half of the previous images, which were now much cleaner and nicer looking.
The file header still showed the same 140 gain (and offset is not reported from these cameras, a complaint I have made before).
I don't know what went wrong, but I don't want this to ever happen again. I lost over an hour of non-recoverable imaging time (which is precious for me)
Any help is appreciated
