Sadr and surroundings NGC 6888

It feels like the raw FIT looked better after photometric calibration, and I didn't quite get something right with the masks and curves. I'll do a minimal processing later for comparison.

Sometimes the sequence matters. If photometry is done first, and then when subtracting the background, calibration comes out fine. But if on the same raw data you do the subtraction first and then photometry, it's fine too. It varies across different source files, and I don't quite understand what it's tied to, but this Siril algorithm messes with your head. It's a similar story with math: you try to apply a formula, and you get garbage. I found a workaround — I first apply one function that always works properly; it takes two layers and makes a normal image out of them, and inside Siril it apparently does something else. Then I apply the formula that was working incorrectly, and everything works. In short, it's magic. You have to go through one stage several times from different angles, and somehow an understanding of the algorithms starts to emerge.

That's for sure, one session is never enough. With experience, you start to understand a bit what to apply where. At first, you just follow a template like on YouTube, but everyone's material is different, so you have to deviate from the template.