M16 - narrow field LRGB

[codemonkey]

Why? Well, I needed to fill the gap between galaxies of interest...

Probably should have just done the usual SHO, I don't think RGB is flattering on the eagle. Not terribly proud of this effort, but I'm not sure I can do much better with the data, so here it is.

Full res available on Astrobin (https://www.astrobin.com/409532)

And now I'll go back to galaxy imaging, should my equipment and the weather be in agreement.

[multiweb]

Beautiful colours and details. Love M16. :thumbsup: After M8 :P

[JA]

Very nice Lee :thumbsup:

Best
JA

[Atmos]

I totally agree with you Lee, it sucks ;) :lol:
Love the star colours and you’ve managed some good detail without using a Ha filter which is impressive :) There are some deconvolution worms showing through (I have the same disease that Mike does) but as you say, it’s about as good as it gets with LRGB on this region.

[strongmanmike]

Hi Lee

That to me looks like a HaRGB, not LRGB..?

Well, I really like the HaRGB palette on the Eagle actually and you have produced another really nice job here mate :thumbsup:

Mike

[codemonkey]

Thanks Marc and JA :-) Agreed on M8, Marc... I might sink some time into that soon, if I can get my equipment back up and running and the weather is agreeable. Winter has hit here and with it has come the thick fog we get every year, so not sure how I'll go for the next few months...

Colin... I think I'm going to need to start employing you and Mike to do QA on my images before I post 'em :p I'll have a closer look at the decon and see what I can do.

I'm not so sure this is as good as it gets in LRGB on this region, but I don't think I can do much better with this data.

Thanks Mike :-) It's definitely just LRGB... I haven't used my narrowband filters in ages; I'm almost thinking about selling them.

[strongmanmike]

Well then...wow, it is even more excellent :thumbsup:

Mike

[strongmanmike]

No problemo, happy to :thumbsup: :lol:...although I didn't see much at all in this image :question:

Mike

[codemonkey]

Thanks Mike :-)



Yeah, I couldn't see much either... there were some light ringing artefacts around the pillars, which is what I'm guessing Colin was referring to. I've fixed that now.

I've also reduced the stars fairly significantly by carefully mixing in a starless version generated by Starnet++ ... I think it looks better. I've left the original up both here and on Astrobin so people can compare.

[alpal]

Hi Lee,
that's a great image and nicely processed.
What was the seeing like on the night?
It doesn't look like it was better than 3 arc seconds?


cheers
Allan

[codemonkey]

Cheers Allan. This was imaged over several nights. Jetstream was reportedly horrible over all of those nights. Guiding was actually good. I think it's at least partially due to the optical issues I've been having lately... have what appears to be astigmatism which will cause softness in the focused image. Trying to work through that now.

L data came in at 2.7" (x) / 2.55" (y) FWHM... keep in mind this is at 0.5"/px so it's heavily oversampled and will thus look softer than it would at >= 1"/px

[alpal]

Hi Lee,

2.7 to 2.5 arc seconds FWHM is fairly good -
so yes it should have looked slightly sharper.
Why have you had optical issues lately - what's changed?


cheers
Allan

[codemonkey]

To be honest 2.7 - 2.5 is very soft and at 0.5"/px I wouldn't expect it to look any sharper than it does.

Not sure re the optical issues. I've thrown out tonnes of data due to elongation... it's not the mount, tracking/guiding is great.

Elongation exists in very short (i.e. 5 second) exposures, and was flipping 90 degrees either side of focus... classic astigmatism. Most recently it's very elongated on one side of focus, and much more round on the other side, which I don't understand.

I've found that a mere 8-16 microns of focus is the difference between eccentricity of 0.6 and 0.4 and SGP just doesn't get it that close most of the time.

From the testing I've done it looks like either issues with the secondary, or the primary cell. Didn't rotate the the primary mirror, nor with the camera+coma corrector, so the things
that stayed stationary are suspect (mostly the secondary, secondary mounting and primary cell). Could be the adhesive they used to stick the secondary on has changed over time. Could just be that thick chunk of aluminium that is the secondary stalk is changing temperature at a different rate to the secondary and deforming it.

I've ordered a new primary cell but it hasn't left Germany yet. Will try that first but to be honest I don't think the problem is in the primary cell... there's been a couple of minor things bothering me about it though so it was a good excuse to get a new one.

If the new primary cell doesn't resolve it, I'm going to try re-gluing the secondary with some carbon fibre in between the mirror and the stalk.

Since the optics were tested by TS before they sold it to me and I didn't have the issues in the past, I don't think it's anything inherent in the mirrors... but yeah, not 100% sure what it is yet.

[Andy01]

Nice rich colours on a classic favourite- I prefer the smaller stars version too :thumbsup:

[alpal]

Thanks Lee,
I just had a look at some of your previous pictures
& they seem to have nice razor sharp diffraction spikes on
the bright stars which are clearly not there in this latest picture.
I wouldn't know how to fault find it other than substitution as you're doing.
Maybe other more experienced imagers here would have some tips?


cheers
Allan

[codemonkey]

Cheers mate :-) Also note that this was imaged on the same nights as Centaurus A. Seeing can change quickly, but I think the general trend was consistent between the images.

Yeah, I've made a couple of threads on various forums to get some advice from those more experienced with newts than I am... got some good advice but mostly just confirming all of the things I already thought.

[gregbradley]

That's a wonderful M16 and I really like the lovely saturated yet natural looking colour.

Very nice indeed.

Greg.

[strongmanmike]

For me the original is better, more crisp and vibrant a pretty damn good M16 image really...tough and confusing game this astroimaging huh? Canni please everyone :lol: :)

Mike

[codemonkey]

Thanks Greg :-)

Mike, yeah, I hear ya. I think the reprocess is a little softer, but not by much. I think the reduced stars enhances the softness...

[Paul Haese]

Looks pretty good to me Lee. No apparent problems with the stars, have you got that fixed now? Looks it to me.

I like the detail and the colour, though I wonder if there is more lurking in the colour palette.

[willik]

Very good detail but the colour is little to red for me but still a good image and processing takes time :thumbsup:
Martin

[Placidus]

It's refreshing to see a wideband image, because it reminds us just how many big bright stars there are. It's a star-forming region, and there they are, all formed and everything.

The "reluctant parachutist" just below-right of centre came out very well.

[Slawomir]

A very pleasing image Lee. I really like how you processed LRGB data. Stars and everything looks great :thumbsup: