Deep Pismis 24 and NGC 6357 - with Hubble comparison

[SkyViking]

Hi All,

I took this image during four nights in July. It covers the central part of the large nebula NGC 6357, also known as the 'Lobster' or 'War and Peace' nebula.
This nebula appears intensely red, a striking contrast to most emission nebulae that are somewhat more magenta.
The central part of the nebula near Pismis 24 is very bright and I managed to get some fairly good resolution in that area so I made a comparison with images from La Silla and the Hubble Space Telescope. Interestingly, this image taken with a 10" telescope is really not much behind the ESO La Silla image that was taken with the Danish 1.5 metre telescope. The Hubble view is of course another story, but a fun comparison still.

Link to large image 75% size (1.7MB): http://www.pbase.com/rolfolsen/image/144888604/original
Link to high-resolution comparison of Pismis 24 with images from La Silla and the Hubble Space Telescope: http://www.pbase.com/rolfolsen/image/144888612/original

About the image:
At the center of the nebula lies a small star cluster Pismis 24 containing some of the heaviest stars known. The intense ultraviolet radiation from these stars is slowly eroding the surrounding gas and dust away and shaping the delicate structures visible throughout the region. The heaviest of these stars, designated Pismis 24-1, was long thought to weigh some 200 to 300 solar masses, well in excess of the theoretical upper mass limit of about 150 solar masses for an individual star.
But in 2006 high-resolution images taken with the Hubble Space Telescope showed that Pismis 24-1 is really two stars orbiting one another. Further to this, ground-based spectroscopic studies have revealed one of the stars to be a tight binary. Still, these three stars are among the heaviest known.
The cluster and nebula lies 8000 light years away in the constellation Scorpius.

Image details:
Date: 7th, 8th, 10th and 17th July 2012
Exposure: LRGB: 340:50:42:46m, total 7hrs 58mins @ -30C
Telescope: 10" Serrurier Truss Newtonian f/5
Camera: QSI 683wsg with Lodestar guider
Filters: Astrodon LRGB E-Series Gen 2
Taken from my observatory in Auckland, New Zealand

Hope you enjoy the view. Comments and critique welcome as usual.

Regards,
Rolf

[alpal]

Nice pic & an interesting write-up - thanks.

[John Hothersall]

Your detail is incredibly close to the professional results. Amazing the detailed gas structure that can be achieved with amature scopes.

John.

[DavidU]

Very cool. I think if you had better seeing your image would be closer to the 1.5m image. Well done.

[RickS]

That's a very impressive piece of work, Rolf!

[jsmoraes]

Very intersting comparison. What I see, it is an appearence of lack the focus, between your photo and La Sillas' photo. But the details are fully present. Congratulations by your imaging, and very good idea compare those photos. Thank you for share the image and description

[strongmanmike]

Excellent Rolf and love the comparison, I did the same thing back in July 2010 with the Starfire (on a rare night of reasonable seeing), it's fun to do. That combo you have running there in your enquiring hands is both breathing fresh air into long in the tooth objects and showcasing more obscure things, loving it mate :thumbsup:

Mike

[Stevec35]

Great stuff Rolf. I wish that I would have had time to see your setup when I was in Auckland.

Cheers

Steve

[Ross G]

An amazing capture Rolf.

Thanks.

Ross.

[SkyViking]

Thanks alpal, glad you enjoyed it :)


Thank you John :) Yes I was surprised that the resolution was so close to the La Silla image, theirs is maybe a factor 2 better but that's with a 1.5m scope.


Thanks David, the seeing was actually pretty average while I shot this so on a steady night it could probably be better :thumbsup:


Thank you Rick :)


Thanks Jorge, yes I agree the La Silla image is just a bit sharper. These comparisons are quite fun to do :)


Thank you Mike :) I remember your comparison and it was what prompted me to try it with this one. I'm glad you enjoy the images, I'm having great fun producing them. I have made a list of targets to keep me busy but this one was a bit of an experiment as I didn't know how much I could expect to gather of the big nebula - it turned out to be quite a lot!


Thanks very much Steve, hopefully there'll be a next time! :)


Thank you Ross :)

[silv]

amazing and astonishing comparison.

do you know what kind of camera/imaging process the 2 professional versions were captured with?

your QSI is a 8.3MP and your image in the triptych looks as if it's zoomed-in and lacks pixel info. (and focus).
what I want to ask is:
disregarding the magnification of a 10",
would your image have benefited from a 16MP camera chip?
(not that such a camera would be affordable - just a theoretical newbie question)

[iceman]

Lovely image Rolf, nicely done.

[SkyViking]

Thanks silv, I'm not sure which camera was used for the La Silla image but the Hubble image was taken with the ACS/WFC, ACS/HRC and WFPC2 instruments. I don't know the specs of those but it should be possible to look up somewhere. The Hubble image details are here: http://hubblesite.org/newscenter/archive/releases/2006/54/fastfacts/

Yes the comparison is made just on a very small zoomed portion of the main image, hence the blurred appearance in my image. A 16MPixel chip would not have increased the resolution in my case since the 8300 chip already has fairly small pixels, it would instead provide a larger field of view for the main image.


Cheers Mike, I'm glad you enjoyed it. :)