I'm puzzled by a few large round image artefacts that appear in the lower right corner of my image of M33. After careful inspection of my imaging train (telescope, ccd, reducer/ flatterner, filter), I couldn't find anything to explain them.
The technical info:
TV85
TV reducer/flattener 0.8
Optolong L-pro
ZWO ASI533MC Pro
35x300s lights dithered
No calibration frames
The attached image is only DBE and non-linear stretched in PixInsight
Bortle class 6
30-40 degrees above the city skyline
Any suggestions would be appreciated
Have you checked all of your subs to make sure it’s not just 1 or 2 that have something in them that has appeared on the stack ?
I had a similar pair of spots in my DSLR that I could never find any reason for. They don’t look like they’re anything flats wouldn’t take car of but I understand your want to know what it causing it.
Thanks Ryan!
I'll have a look and see. The problem is they only show after DBE in PixInsight. I'll take a few flats today and see whether the artefacts show on the flats.