I have data from 2 nights of the Rosette Nebula. Everything worked great the first night. I used the mono_preprocessing script with lights, darks, flats, and dark flats (ASI 1600MM-Cool). After that, I used GraXpert on each separate channel (S, Ha, O) and created processed, but unstretched FITs. Then I used RGB Compositing in Siril to combine them in the SHO palette and it worked great (with clean up following).
So come to night 2. I go through the GraXpert step and everything was fine. When I open the Sulfur channel FIT in Siril and AutoStretch it, it looks great. BUT when I add it to the Red channel in RGB Compositing, I only see stars. The Blue and Green with Ha and O respectively look fine. When combined, it doesn’t even look like it aligned correctly.
I’ve attached 3 images, one of the R channel from the first night, the R (sulfur) channel from the 2nd night, and the sulfur channel opened in Siril. You can see the first night, it shows up as a stretched sulfur image of the Rosette Nebula. In the second, there’s no DSO and given the way it aligned, I’m not even sure it’s the right stars. I don’t think the problem is GraXpert since I can load the resulting FIT in Siril and it stretches fine (3rd image).
Thanks for any help!
Night 1 - Red/sulfur tab. Everything looks great.
Night 2 - Red/sulfur tab. No DSO. Not even 100% sure the stars are right given it wouldn’t align.
Night 2 - FIT opened on its own. Looks fine.
