M31 (highlighting regions with Ha)

Ryjov Aleksey

2714944

Deep Sky

Feb 27th, 2026

665

NGC 224NGC 206NGC 205NGC 221

Resolution:: 5749x3733 px
File size:: 1943 KB

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Photo description / processing

The shooting was carried out over several days: from the end of August to mid-September 2025. Part of the material was shot under an almost full moon. I used all the capabilities of Ricardo's new Siril scripts, and also used pixel math in Siril to add narrowband H-alpha (Ha) data to the broadband RGB image.

Technical information

Telescope/Lens: Askar SQA 85 мм f/4.8
Camera: ZWO ASI 2600 MC Pro
Mount: Ioptron HAE 29 C
Guide Scope: Askar 52 мм F4
Guide Camera: ZWO ASI 120 MM mini
Software: SharpCap 4.0, Siril, GraXpert

Location: Петушки, Владимирская область, Россия

Light pollution

Orange, Bortle 6 zone

Date taken: Sep 15th, 2025

Exposure

236 × 180″ · ISO/Gain: 100 · RGB
101 × 300″ · ISO/Gain: 100 · Askar D1 DUO (Oiii+Ha) 6 нм

Total exposure: 20 h 13 m

Comments

Jim Holden

Excellent work! I could spend hours exploring the details!

Feb 28th, 2026

Ryjov AlekseyReply to Jim Holden

Thank you! Indeed, the Ha filter highlights the details, revealing a large number of nebulae within the structure of M 31.

Feb 28th, 2026

NickolayReply to Ryjov Aleksey

How do you figure out how much hydrogen to accumulate? You have quite a lot, almost half. Would 2 hours through a dual-band filter be enough for me, for example, for 6 hours of RGB?

Sep 7th, 2026

Ryjov AlekseyReply to Nickolay

I think yes, for a start. We need to try it, understand the processing principle, and then it will become clearer.
Here is a detailed instruction on how to do this in Siril using pixel math: https://www.youtube.com/watch?v=77gZfGdI8aA&t=21s

Sep 7th, 2026

NickolayReply to Ryjov Aleksey

Oh, thank you, I'll take a look.

Sep 7th, 2026