I did some poking around, it seemed M51 under Ha narrowband did not show as much detail as R filter, so last night I gave it a try with R filter. Unfortunately my low budget AVX mount could not keep up with my C8 at prime focus. Struggled all early morning only had a single light and single dark to work with.
C8 F10/FL2030mm
Polemaster
Celestron OAG
224mc as guider
Minicam5F imaging
R 1x600s, -25C, no darks no biases no flats.
The camera has the same chip as ASI120mc, but has TEC cooling and built in motorized filter wheel.
For comparison, I have been very lucky with M1 using the same setup. Below is also M1 in Ha 13x900s, 5 darks and -25C.
My speculation is, M51 is much closer to north pole and has smaller movement, as such the AVX periodic error movement became relatively severe, and PHD kept trying to correct it but failed to do so.
Or it could just that I was sleep walking through the session, had no idea what I was doing. I did have an excuse, I was under the weather last night.
