Dew on primary mirror of Mak-Newt (Skywatcher 190MN) or something else?

Sky-Watcher Starlux 190MN / BK 190MN DS Troubleshooting Artifacts
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Craig Dixon avatar
Craig Dixon avatar
Attached is a screenshot of a 3 hour stack of 15 second subs (This is UV/IR data for the stars only to complete a project). Could this be dew on the primary mirror:



I've also noticed that if I zoom in, the noise pattern is shockingly blotchy. This is a 1:1 view:

Of could this be an issue with a process within WBPP?
andrea tasselli avatar
andrea tasselli avatar
There is no dew on primary in Maks, it just doesn't happen (well, unless you are at 100% saturation). And even if it were (which is exceedingly unlikely) it would show as a general dimming of the image, that's all. Dew on corrector would be far more easily occuring though. The grainy look is just due to the short subs you're using, which means loads of RON to deal with.
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Craig Dixon avatar
Craig Dixon avatar
The morning after I  shot this data, I looked down the tube and there was condensation in the middle of the primary mirror. I can't say for sure whether this formed during the night whilst data was being collected or in the morning but it was definitely there.

Do you think this data is useable just for the stars?
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andrea tasselli avatar
andrea tasselli avatar
I guess you reached 100% humidity late in the night and given the very muggy day of yesterday that won't surprise me one bit. Chin up as at least you got clear skies while I get only clouds. Yes, the data is perfectly useable.
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