New Image: LDN753 in NB + RGB

[Stuart Heggie]

LDN753 is the centre of a host of LDN, LBN and Sharpless targets all within the small constellation of Sagitta. A newly discovered arc in OIII was what I was hoping to capture.

https://www.astrofoto.ca/stuartheggie/ccd_photos/LDN_753_HOO+RGB_AP155_G4_June2025.html

18/18/18 x 10 min each of RGB, 22x20 min Ha, 32x20 min OIII
Camera: Moravian G4 (16803) w Gen II Astrodon filters
Scope: Astrophysics AP155EDF Refractor w Focus Boss II
Mount: Paramount MX
Guiding SBIG ST402ME attached to a Borg 60mm guidescope
RGB and Ha and OIII processing in PixInsight
RGB: SPCC, BlurX, NoiseX, StarX, Curves, HT, masked Saturation Boost (via Curves), Stars Back In
Ha and OIII: BlurX, NoiseX, StarX, Curves, HT then combined the Ha and OIII via Foraxx script.

Photoshop: Layered the RGB over the Foraxx narrowband data using Screen. Some tweaks and a slight crop.

Click on the image to see ~ 2x and to re-size it for your browser.

Lucknow, Ontario
June 2025

BTW - an amazing version that inspired me to try this by Bray Falls and can be seen here: https://app.astrobin.com/i/v4znmz?r=0

Stuart Heggie

https://www.stuartheggie.com/f783431253

[Francesco Meschia]

Thanks for sharing your image, Stuart! It's beautiful, and I find that strange OIII bubble very intriguing. Do you know if it's a PN or an SNR?

It seems as if the noise reduction done by NoiseX left some (slight) medium-to-large scale blotchiness. Are you using the AI version 3, and if so with what parameters?

Francesco

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[Stuart Heggie]

Francesco, thanks! I am using v2 of NoiseX. I am not convinced this is the root cause of the uneven background tho. (I could be convinced of course)

This object is super faint and I had to stretch my data way more than normal to get what I got. I "think" I pointed out that Bray Falls' image is super deep. At my f-ratio, I would need over 300 hours to match how deep his shot is. I got around 20 hours of data. So ... probably I was stretching a lot of noise in the background.

As to what "it" is ... I don't think it's a PN or SNR but I don't know. As a recent discovery, it's possible nobody knows yet. I haven't done enough research on it to say.

Stuart Heggie

https://www.stuartheggie.com/f783431253

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