Last night we finally had a clear-ish late evening sky - SQM 18.79. I noticed M63, an old friend, was well positioned so I moved in for some time with it.
Skies seemed clear but it was windy - 10-15 mph and gusty I estimate. I was running flats and darks and messed with the histo to the best of my ability but I could not remove the noise(?) pattern you see in this cropped image. I've begun using a TG 365 cover on the mount/scope and noticed the collimate knobs had loosened - probably from friction with the cover as I remove and replace it. Doesn't seem like a collimation thing but I plan to re-collimate and tighten all the adjusters so there's more tension holding them where I leave them. Unfortunately they protrude from the back end of the carbon fiber tube of the TS scope - talking with TS about that.
Anyway, please click to enlarge and have a look. Share any ideas you have on what causes this.
M63 Sunflower Galaxy: ASI 294 MC, 71 frames/ 8 sec/ 300 gain/ 203mm F4 Newtonian