How to Stack Fits and Raw files in one go?

Stack the bias and dark frames on their own, save them as fits and use them to calibrate the lights.

Jens, I had exactly the same issue. Same gear too - ASIAIR mini & Canon 600D. The files are, sadly, incompatible. You can stack them separately, but they will not calibrate as they are different dimensions. It’s not worth cropping or resizing them. Sorry.

Luckily you can retake bias files with the ASIAIR really quickly, and if you wait for a night with comparable temps, bring the rig rig outside and just grab some new darks. You didn’t mention anything about flats, so I’m hoping the rig is still in the same config (rotation, filter) so that you can take those with the ASIAIR too. If not, just take flats anyway (same filter) and you might have to remove some dust donuts manually but at least it’ll sort the vignetting.

I had to retake calibration frames for a month of imaging done before I realized this would be an issue, and I’ve had to completely rebuild my darks library.

Good luck and clear skies!
Mark

When I was using a non-cooled camera, I used to keep a library of darks the best I could with about 5 degree C gaps. So I had my fridge darks and my basement darks and a few in between taken on random nights. I would even be known to grab just my camera body and laptop and leave in outside under a towel on a moon filled night and wait for the temp to get close to that gap in my library. It wasn't perfect but I doubt it was at all noticeable in my final product. I would do anything to avoid wasting good imaging time on taking darks.

Jens:
that's actually a good idea, I've never informed myself if it makes a huge difference if the darks aren't captured at the exact same temperatures as the Light frames. It is always such a hustle to do. I started to put the cap on here and there just to capture the darks during the imaging. I wouldn't have the patience to wait for the darks to be finished.

Edit: I just looked at your images, how in the world did you get such clean and noiseless images out of the Alpha 6000 and the R. is that all due to the darks you just mentioned?

Thank you. Not at all, the darks help a lot with the A7R which has some amp glow when shooting over 2 minutes but the A6000 is so clean that darks are almost (but not entirely) optional. Remember that although there are flaws and issues with these cameras (star eater), the sensor in the A7R was actually used in astro cameras and the A6000 sensor is a not too distant relative of the now famous IMX571/ASI2600. Integration time is the number one factor. You will notice that those images are mostly 6h or more from moderate B5 skies. Next is dithering to average out a lot of the noise and guiding. Beyond that, never drizzle an OSC or SLR if you can avoid it (to many people recommend this to beginners) and careful application of AI denoise is amazing. For most of those shots I used the free AstroDenoisePY but on my mono shots I've since bought NoiseXterminator which I can't recommend enough. As a bonus, it will work in Affinity and PhotoShop so no absolute need to invest in Pixinsight to take advantage of it.

To show a comparison of how processing skills can help, I have 2 shots of Andromeda in my gallery. The first was was processed with about 6 months of experience with almost all free software. Even that was a re-process of the original data. My OG of that was rough. The second is with about 18 months of experience and paid for software. I still have a ton to learn and a ton of room for improvement but I can see a huge difference between the 2. All of it was my original data from the A6000 and my rookie capture skills.

Don't think about changing your camera though. Keep your Canon, it has it's own advantages and is a great tool. When it comes time for a new camera go with an Astro specific and preferably cooled one. I skipped over OSC Astro cameras and right into mono imaging. Your Canon can get you enough skills to do the same if you want. You are off to a great start.