JohnG:
Thanks for that advice . Now that I think back about the night, NGC 253 was the first imaging run of the night. I think I should have left the camera outside for a while even if not attached whilst drifting aligning/star alignment; to allow it to cool to outside ambient temp; then done at least 10 or more subs with good delays in between.
I check the one sub and it shows the banding and glow in the corner.
Thanks for the advice
