Helix Nebula - Request for Help/Advice

[AdamJL]

Hi all

Not really a "share" thread, more a request for info from others who have shot this faint target.

I've been playing about with it today, and am not really anywhere near ready to share the final image. In fact, I've decided that this is going to be a multi-year project because I'd like to capture as much SII as possible, but it's really faint!

But my question is around any potential faint Ha regions around this object. I never really see any in other images. I tend to see varying degrees of stretching of the object itself, but I always see it sitting in a dark background.

Maybe I just didn't do a good enough job on DBE, but I sure tried!! I've shared a starting-progress image here. Has anyone seen these fainter Ha regions around this object or have I just stuffed up somehow? Probably the latter, but I'm just curious.

[AdamJL]

here's a before/after DBE on linear data. Could it be that the DBE added these regions in? I can see some faint differences in the after image.

[ChrisD]

I think you've got good data for the surrounding Ha.

This image shot by Trần Hạ confirms it:
Helix Nebula (https://www.astrobin.com/392141/)

[AdamJL]

Hi Chris

Thanks for posting that... I think it's confirmed my suspicions. I've got something wrong in my flow.

The reason is that Trần has picked up the fainter outer shell (I haven't), but hasn't picked up as much background nebulosity (only some very very faint data), because there isn't really any of much significance. So that means my background Ha is something being introduced either from my flats, or editing workflow.

Back to the drawing board :) thanks again

[Nikolas]

The secret to this object is acquisition, you really need many hours of acquisition in order to bring out the faint nebulosity.

If you search helix nebula on astrobin there are some amazing images and the process involved.

[AdamJL]

No doubt. I'm on 5 hours so far on Ha, but that doesn't explain the blotchy background.

here's what I mean. Comparing my image to Trần's.

I'm "picking up" much more faint background data, but Trần is picking up more of the outer shell. That tells me my data is bad, because if I can pick up the fainter stuff, I should also be getting the shell, and even on a heavy stretch, I'm not.

[Nikolas]

What telescope/camera system are you using as opposed to Tran's? Also what bortle sky are you in comparted to him?, Are your acquisitions similar? There are many reasons why your images differ so the more info you can provide for both the better we can assist.

This is Tran's data times and filters
Astrodon 1.25" 3nm OIII: 32x900" (8h) (gain: 200.00) -15°C bin 1x1
Astrodon 1.25" 3nm SII: 52x900" (13h) (gain: 200.00) -15°C bin 1x1
Custom Scientific H-alpha 3nm: 47x900" (11h 45') (gain: 200.00) -15°C bin 1x1

[AdamJL]

268M + Antlia 3nm filters on Esprit 120 at f/7
O3 was - 12 x 300s and 32 x 400s
Ha was - 44 x 300s
(no SII yet)

The issue is in Ha only. O3 was in a B3 location at New Moon. Ha was at a B3 location at Full Moon (but with decent separation, see attached). Trần's got longer subs (so I'm guessing not a light polluted area!) and is also picking up more stars.

I've raised this over on another Discord channel too; they seem to also think it's just bad calibration on my end, unless the 268M is good enough to pick up hydrogen emissions no one has ever seen :D
But that said, I'm still not 100% sure, because I can definitely see some background nebulosity in Trần's image, it's just much much more faint than mine.
Some of this nebulosity even lines up with the areas I'm picking it up.

[AdamJL]

Think I solved it. It's a PixInsight thing...

DSS on the left, PI on the right. DSS did it well, PI...well, you can see the difference.