This project has been a nightmare but fortunately is over and brought me a beautiful image of M101, the better I have, actually!
I decided to go with M101 in February, using my CLS filter (IDAS) and picking up HA with the L-Ultimate but things didn't go smooth at all.
Due to dew issues, I had to discard almost half of the frames and then ... the integration showed an horrible "rainbow" in the lower part
.
I suspect this was due to some stray light from neighbour but it was the first time I ever saw it and I couldn't find the source (long story short: does not appear on L-Ultra, I've never seen it before, and after, that sessions, I changed the filter to the new Antlia Triband RGB Ultra and never saw it again).
Unfortunately, I couldn't identify this stray light on a single frame and I had to find other solutions:
- I did several attempt to blindly stack a subset of the frames (discarding one night a time first and then trying with the first part of the night or the second to see if the problem was aiming towards a certain direction ...): nope
- I tried to to remove this "rainbow" in the final stack (I even tried some AI tool, I was desperate!)
At last, I decided to discard all of them and start over, keeping only the L-Ultimate frames for HA.
So I started again in May (we had months of rain here, with flooding and disasters ...) using the new Antlia Triband RGB Ultra and I got this image.
Unfortunately, I couldn't match the camera rotation very precisely (I'm waiting for ZWO CAA availablity to solve this issue) between the first and the second session so I had to crop the image considerably.
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