C/2025 A6 (Lemmon)

Alex Ch

1892985

Comets

Oct 4th, 2025

666

Resolution:: 5331x3467 px
File size:: 28591 KB

Photo description / processing

Understood that I don't know how to process comets, can't separate the tail from star trails and properly overlay it on the background with static stars.

Technical information

Telescope/Lens: Sky-Watcher 150/600 Quattro
Camera: Canon 200D
Mount: Sky-Watcher HEQ5 PRO
Guide Scope: 60 mm Guide Scope
Guide Camera: ZWO ASI 178MM
Accessories: Zwo Asi Air Plus, СС 0, 85х
Software: DSS, Pixinsight, PhotoShop

Location: Новосибирская область, Усть-Каменка, Россия

Date taken: Sep 30th, 2025

Exposure

70 × 90″ · ISO/Gain: 3200

Total exposure: 1 h 45 m

Comments

Iren

I don't know how either. But you have good source material. I actually shot the comet from the city because there was simply no other option. At least you can see the tail clearly in yours. Mine is just choppy in places. I don't even want to post it.

Oct 4th, 2025

Alex ChReply to Iren

Post them! This will serve as a starting point for comet processing. I consider it one of the most challenging aspects of astrophotography.

Oct 4th, 2025

IrenReply to Alex Ch

Agreed, I didn't think it would be sooo difficult.

Oct 4th, 2025

IrenReply to Alex Ch

By the way, try stacking in Siril as well. You can stack the comet and the stars separately with calibration, adjust the background, and align both images to the same size. Then, in PixInsight, remove the stars from the frame where the comet is trailed using StarNet, and overlay it onto the comet stack using PixelMatch. You just need to refine the comet stack a bit. It should turn out beautifully =)

Oct 4th, 2025

Alex ChReply to Iren

Yes, I've been thinking about Siril, I really need to learn it in more detail! Thank you so much for your attention to my work!

Oct 4th, 2025

Nickolay

Have you tried the comet and stars mode in DSS?

Oct 4th, 2025

Alex ChReply to Nickolay

Yes, I tried, but unfortunately it didn't yield a positive result. I stacked it in DSS. There's a stack for the comet, exactly here it is, and a separate stack for the stars. But the image did turn out noisy, of course—for a camera at ISO 3200, that's apparently beyond the limit for a dynamic object.

Oct 4th, 2025

IrenReply to Nickolay

I tried. But I didn't like the final image after calibration. Stacking artifacts and vignetting started to appear. I liked Siril better. At least you can do calibration and background leveling right away there.

Oct 4th, 2025