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Old 08-11-2020, 11:30 AM
vesko
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M33 image artefacts?

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
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  #2  
Old 08-11-2020, 12:10 PM
RyanJones
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Hi Vesko,

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.
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Old 08-11-2020, 12:37 PM
vesko
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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.
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Old 09-11-2020, 08:44 AM
Zuts
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They look like dust bunnies to me, I have had similar and find they move around whenever I clean. Flats will take care of them.
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Old 09-11-2020, 09:03 AM
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The_bluester (Paul)
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Dust bunnies is my call as well. They are inevitable on images. Flats will deal with them.

Those are pretty minor ones, you would probably be lucky to pick them on individual subs unless you stretch them like mad.
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Old 10-11-2020, 01:15 PM
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gregbradley
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They are definitely dust specks on your filter most likely but also it could be on your sensor window.

Clean them off or use flats which remove them when applied to the image.

Greg.
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