I am at a loss and hope someone can help.
I am having problems with my luminance filter photos as I see a line in the middle of the photo which I assume is from my sensor. I have taken bias/flats/darks etc but they do not remove it during the stacking process. Attached is a photo from a flat showing clearly the line through the middle of the photo (is this normal?) and another photo zoomed in showing the line clearly through M81. I would have thought the line would have been corrected during the integration process - what am I doing wrong?
Many thanks in advance for your steer