Tutorial:
Siril for pre processing astrophotos

Content:

1. My personal parameters when using Siril
2. Desaturate stars
3. Star Color calibration
4. Calibration tests
5. Dark calibration analyze
6. Adjust the flat calibration with a fake bias
7. Meridian flip and stacking
8. To be continued

Note:
I take no responsibility or liability for what are written here, you use the information at your own risk!

7, Meridian flip and stacking

In earlier pre processing software I have used it was always complicated to handle a rotated image. Example, when the mount do a meridian flip the photo will be upside down relative the earlier ones. The bias, dark and flat calibration should not be rotated but the background remove should follow the camera orientation. The camera, a Canon 6D has it auto rotation disabled.

Lately I took a longer exposure, more than 2 hours, it passed the meridian even when I had a delay of one hour. Will this rotation mess up my photos or can Siril handle this ?

The control system is the KStars with Ekos/Indi. It handle the meridian flip by automatic and it's possible to delay the flip. But check that the camera doesn't hit the mount before setup a delay. It handle the auto guiding and do a new calibration of the auto guiding system and also a new plate solving, all without any assist from me. Have a look here: Raspberry Pi4 system

Meridian flip and stacking:

I do the normal pre processing: Dark calibration, Background extraction, Flat calibration, align and at the end stacking the images.

There were no need to setup the process to tell that some of the photos was rotated in any part of the process. It just worked, fantastic ! In the upper left corner there is a sign that the camera isn't exactly 90 degrees rotated relative the DEC axis. I need to crop the image a bit extra because of that. Later I can align the camera better, but it depends a bit of the precision of the Vixen dove tail and I use the camera system on different mounts.