M48 and M65+M66 – finally with round stars

The past months I had trouble with my 10 inch scope. I was not able to image with nice round stars. So i kept imaging with my smaller refractor, as stars were rendered round. After some investigation and chat with fellow astronomy club members, I could nail down the cause of the elongated and triangular stars: the auto-guider as well as a too short settle time after dithering were messing up. So, to achieve the round stars everyone is after, I had to increase the settle time after dithering (otherwise, I got double-images due to the offset) as well as the guiding parameters in MGEN. My settings for off-axis guiding on 1250mm focal length are: Threshold: 0.1, Aggressivness: 100% in RA and 80% in DEC and 2×2 binning.

The first test target was M48 with 50% aggressiveness. Stars were not yet fine. The second target was M65 together with M66. Stars are fine!

Image data:
Date: 2021-03-31
Location: Graz, Austria
Telescope: 10″ f/5 Newtonian with GPU corrector (1250mm focal length)
Camera: QHY183M @ -20C
Filters: Optolong RGB
Guiding: MGEN-II with off-axis guider
M48: 83x10s L, 46x20s R, 30x20s G, 30x20s B
M65+M66: 48x60s L, 39x60s R, 32x60s G, 20x60s B

Leo Triplet with H-alpha and O-iii enhanced

During the last few days there were really promising clear nights. I recorded several data sets from my urban location (under these conditions, going up the mountains would have been a treat!). Now, as there are clouds again, I am processing the captured data. Here is the first result from the Leo Triplet (M65, M66 and NGC 3628).
I still have not yet received my color filters. So here I have a combination of luminance (UV-IR-Cut), H-alpha and O-iii data.

Image data:
Date: 2021-02-12 – 2021-02-14
Location: Graz, Austria
Telescope: 102mm f/7 APO with 0.79x flattener (equals to 564mm focal length)
Camera: QHY183M @ -30C
Filters: Baader UV-IR Cut + IDAS LPS-D2, narrow band Ha, Oiii
Guiding: MGEN-II with off-axis guider
Exposures: 41x100s Luminance, 20x300s O-iii (2x binning), 30x300s H-alpha (2x binning)
Sky-Quality: 19.4-19.6 mpss