I have been battling my EQM-35 mount and the optics/cameras on it. I reworked the mount and double checked the optics, including the guide scope, as well as testing the cameras. I then took data on the M81 group on March 10 and March 18, 2024 to test everything. I was previously encountering "hairbrush" noise, streaky stuff like brushstrokes of disaster. This time I added a small dither to the image collection because this was a suggestion in the literature to clean up the noise. Based on the image data, from which the posted image above was produced, the reworking yielded a large improvement. The hairbrush noise was gone, making noise correction much less complex. The guiding during the runs was just under 1 arc sec on average, which, while not great, was decent enough to give pretty sharp detail. The stars at the edges were a little funky even though the focal reducer was designed for the scope, but with any camera back spacing issues can arise so I'll have to deal with that by experimenting. At least I now seem to have a decent setup for modestly wide field imaging.
I noticed a small blue patch a bit below and slightly to the right of the center of M81 and checked into that. It turns out that the patch is a satellite galaxy of M81 named Holmberg IX. It is, in fact, a dwarf galaxy that is the youngest of the nearby galaxies with an age of around 200 million years. This link has an image:
https://www.astrobin.com/122555/B/ ASTAP did not identify any variable stars in the field, but it is interesting that Holmberg IX is home to one of two known yellow supergiant eclipsing binary systems (much too far away for it to be resolved in my image).
Pertinent Data:
Integration time 3.5 hours
30 s light images, 20 darks, 20 flats and 20 dark flats
EFL = 512 mm
Bortle 6 skies
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