NGC253, reprocess and more data

[Paul Haese]

My last process of this data revealed lots of detail and some of the halo but I was not overly happy with the results. It looked too contrasted and the colour was dark blue/red. So I collected a bit more data in the colour and reprocessed the data from scratch. My question is what is the actual colour of this galaxy? It's a rhetorical question really.

All I did to answer this question in my mind is push the saturation and boost the contrast a bit but not too much.

I think the colour looks more natural than my previous rendition and the halo is a lot brighter.

Click here (http://paulhaese.net/NGC253RC.html) for image

PS while it might seem like another in the plethora of NGC253's, I remember when Centaurus A was almost the only image in this part of the forum. ;)

[gregbradley]

That's a fantastic image Paul. The blue areas are positively glowing which looks fantastic. The yellow core looks very luminous. An image to be proud of.

Greg.

[RickS]

I don't know what colour NGC 253 really is but that looks great, Paul :thumbsup:

Cheers,
Rick.

[codemonkey]

That's awesome Paul; love it! I was going to ask how much data, but I saw it's on your site ;-)

Very smooth, love the colour, and, well, everything...

[Peter Ward]

What's not to like? A top shelf rendition for sure.
:thumbsup:

[Stevec35]

Hi Paul

I have to admit I'm getting a little over NGC 253 but that's a high quality image to be sure.

Cheers

Steve

[E_ri_k]

Looks great Paul, love the colours. A fine image indeed.
Erik

[alpal]

Hi Paul,
that is a superb image.
I love the colours.
What else could you do - maybe add some Ha subframes?


cheers
Allan

[Paul Haese]

Thanks Greg, Rick, Lee, Peter, Steve and Erik for your comments. I think I can finally put this one to bed now. Bit tired of staring at it too.



Thanks Allan, I don't think I am going to go down the Ha sub frames route at this time. Maybe next year I will collect that and add to some more luminance to collect more data on the back ground galaxies.

[Placidus]

Hi, Paul,

Good before, but the colour is now utterly superb. The colour in the outermost, non-star-forming super-faint area is much better, as is the colour in the distant galaxies, which also seem a tad sharper.

There might be some resultant and inevitable loss of contrast in the beautiful galactic fountain dust streamers, but your streamers are still unbelievably sharp and clear - lovely processing and something to aspire to.

Best,
Mike

[Slawomir]

Looks really really great, worthy printing IMO :thumbsup:

[Paul Haese]

Thanks Mike, there is always a balancing act between contrast and brightness I think. I went back to look at the original image many times and in the end I just thought it needed a reprocess. I kept thinking it looks too dark and the halo is not well shown.

I don't think the streamers are as good as those shown by Jay Gebany in his image but I think my image gives a little of everything.

I did sharpen the background galaxies just a little and that is well spotted.



Thanks Slawomir, the first version appeared in this months A&T. It looked ok but a little dark. This should look better.

[Camelopardalis]

A mighty fine 253 if ever I saw one :thumbsup: if it wasn't for you guys pushing the boundaries some of the rest of us wouldn't have as much to aspire to!

[topheart]

Nailed it!

:)

Tim

[Paul Haese]

Thanks Dunk, its good to push the boundaries of what has been achieved so far. No doubt this will continue to improve every where across the imaging world.



Thanks Tim, still think it could do with a few more hours, but there are more pressing targets on the list that need attention now.

[Shiraz]

pretty much as good as it gets Paul.

The only slight niggle is the asymmetric colour in the halos of the brightest stars - might be worth desaturating them slightly - but that really is nit picking in the extreme.

[Paul Haese]

Thanks Ray. It is kind of weird why this happened. I remember looking at these stars during processing and trying to determine the colour of the three main bright ones. Some images show them as blue and some show them as orange. I will need to consult with a star catalogue to get the actual star spectral type. However, that does not explain how this asymmetric colouring has occurred. I suspect it is just a bit of miss alignment and you have quite rightly pointed it out. I had forgotten about them and considered them as white noise. Time to sort that out and actually find out why that occurred. :)

Edit: I have just reduced this problem a little bit so it is now not as evident.

[marc4darkskies]

That's strange, I thought I'd already commented on this :shrug:

In any case, though probably just a little too saturated for my taste, it's an excellent image Paul! :thumbsup:

Cheers, Marcus

[Paul Haese]

Thanks Marcus. I think you commented on the previous rendering of this data.

I dropped back the saturation just a little. I think that looks better too. It's always interesting to see what others see in an image.

[Shiraz]

looking good. just for interest, the two bright stars are B-V of 0.6 and 0.57, which means they are pretty close to the sun - ie pastel yellow (http://www.vendian.org/mncharity/dir3/starcolor/details.html). The renditions that show them as blue or orange are taking some liberties with the light :).

FWIW, I have had colour oddities on very bright stars when taking colour data on different sides of the meridian - I assume that the scope flexes slightly and the diffraction skirts of the brightest stars do not match up precisely if one colour is taken on a different side from the other two. I haven't tested the theory, since it has only happened occasionally and is easy enough to tidy up.

[gregbradley]

Looking at that image again, its quite a remarkable image. One of your best of which there are many.

Greg.

[RobF]

Stunning image Paul.
Love that egg yolk centre. Mmmmmmm!

Thanks for sharing before 253 fatigue set in. I'm not feeling it at all.....

[Paul Haese]

Ah bugger. I thought those brighter ones were O type stars, the original process showed them to be blue and the second base image showed them to be yellow white. I'll need to fix those now. It is rather odd about the asymmetry. Perhaps you are onto something there Ray. I'll need to test that theory myself.




Thanks Greg, I am pretty happy with the results overall, but as pointed out by Ray there are still a few things that could be fixed.




Thanks Rob, I find it always to be a great object. There are so many interesting things about this galaxy to investigate.

[marco]

:bowdown:

One of your best so far, smooth, detailed, colorful.. perfect!
Cheers
Marco

[Paul Haese]

Thanks Marco. It's one of my favourites too. :)

[nandopg]

Hi Paul,
Fantastic image. Comparing your image with some other images made with "professional" telescopes in sites with very little atmospheric extinction, the color of your image is pretty close the color of those "reference" images.

I think that from the scientific point of view, your image is close to a correct representation of the NGC 253 real .

The full resolution image is so rich in details, that hovering over its surface is a really nice trip.

Thanks for sharing,
Fernando

[Paul Haese]

Thanks Fernando, I viewed a lot of images from lots of sources to get a feel for what I thought was the correct colour in the first instance and then decided that I did not like that colour depth and hence a reprocess. I am much happier with how this looks now. I still really don't know if I have the correct colour as the colour variation presented on the web is quite wide.