Messier 16; real or not real

[Atmos]

Managed a few nights over the latest new moon under dark skies and one of my targets was the Eagle Nebula, not something I've ever really shot in RGB so I wanted to give it a go.

I've reprocessed this a couple of times from scratch and it keeps coming up so I'm inclined to think it may in fact be real. In amongst some of the fainter Ha regions there is the:
Red - hydrogen alpha emission
Pink/purple - mix of hydrogen alpha/beta
Blue - this was unexpected. It doesn't appear like reflection and there seems to be a gradient from purple towards some bluer areas so I'm thinking that there might be some faint dominant Hb emissions within this region.

Higher Res Link (https://www.astrobin.com/full/0h9d5q/0/)

Has anyone ever spotted this before? I've been looking around the inter webs but I haven't been able to find any confirmation on this.

[multiweb]

I reckon the blue in the core is in the right spots looking at various eso pics. Nice widefield. :thumbsup:

[LewisM]

Watch those corners Col...something weird happening there.

Blue seems natural.

[Atmos]

Thanks Marc, I used some of those to make sure that the Pillars region and the reflection nebula nearby had the right colour :)
Towards the top is some bluer regions I haven’t seen before. This usually gets shown as a HaRGB that buries that colour. Or even worse, SHO ;)



There is a few brighter stars within a few ° that can play havoc towards the corners with reflections.
I know I still have about 40 microns of tilt on the left side too :)

[Bart]

I've don't think I've ever seen M16 presented as such so I find it hard to comment on the colour. The central M16 colour looks good and it wouldn't surprise me if the was some reflection nebulosity there as well for the blue, and my goodness, look at all those stars!

[Atmos]

Thanks Bart :) It’s hard to find these things with areas that are rarely shot in JUST RGB.
PixInsight Star detector spotted some 213,000 stars in this field :lol:

[Paul Haese]

Colin, there is certainly some blue reflection within the field but mainly close to the main nebula. The bright O stars there are causing that nebulosity. However, I think the surround blue is probably a little over saturation.

Overall its an interesting looking field and the colour is nice too. I like how the golden stars shine through various areas.

[gregbradley]

I'd say its likely its real. An F3 8 inch scope is collecting a lot of light fast, couple that with your high QE CMOS camera and you are getting deep fast.

I would expect to see things not normally shown with a setup like that.
Wonderful colours by the way. M16 often is boring.

Its like using Fluorite APOs, they pick up subtleties like this.

With the tilt the left hand side will be the right hand side of the camera looking at it from the back of the camera. The top left corner is the bottom right of the actual camera. Keep that in mind or you'll never correct the tilt.
The image is reversed top and bottom and left and right compared to the actual camera looking at it from the back of the camera.

I just relearned that little lesson setting up my Honders again after a hiatus.
Greg.


You probably only need a smallish packer. I use spark plug spacers. You can get a set from Supercheap Auto for a small amount.

Greg.

[Atmos]

Thanks Paul, I believe there is some discolouration being caused by the lack of a luminance (UV/IR) filter. Unlike with a refractor I'm not getting the UV/IR bleed causing larger stars (the IR bleed on my refractor was instantly obvious!) but it does cause some near purple smaller stars across the field. It could also be that the bayer matrix is less than perfect with its cutoffs and that could be causing some colour bleed through the different channels.


One of the real difficulties with this area is that there isn't much many RGB without added Ha to compare against but you are right about amount of light it chews up!

What you're seeing there is ~40 microns of tilt that I'm planning on fixing over this coming full moon period. The ASI094 has an inbuilt tilt adjuster so it's just a matter of dealing with 3 sets of push/pull bolts which is nicer than having to deal with packing out corners :)

[ChrisV]

I've never seen the Eagle quite look like that. A really interesting one. It was great panning through the high res version

[Ryderscope]

Clearly the image that has emerged from the processing is consistent with the data source or the characteristics you mention wouldn’t have survived a number of iterations. Some quite subtle details have been retained throughout resulting in an excellent rendition of this old favourite.