Hi thanks for offering to help. I have tried to upload a couple of FITS files, but there is a file size limit on your website which prevents me from doing this. Please advise how to do this. The FITS files are 10MB each. Instead I can only send you smaller .png files of a single image frame and a single dark frame, both taken at gain 121, offset 10, -15C, 3x3 binning plus a single .jpg file of an aligned and stacked and dark corrected set of images. I have not subtracted darks or dark flats from this image, but doing so separately does not remove the horizontal banding, only some gradient, vignetting and dust motes. The banding becomes much more apparent when the image is stretched. I do not encounter this problem when working at 1x1 or 2x2 binning mode. Please advise what I should do. Thank you.
single image frame
