Thor's Helmet Ha NII OIII 6hrs each

[Placidus]

Thor's Helmet is a Wolf Rayet nebula in Canis Major. H-alpha (red), NII (green), OIII (blue) 6hrs each in 18 1hr subs. Aspen 16M on 20" PlaneWave on MI-750 fork. Field 36' arc, North on the left.

The central star is so massive and violent that its radiation pressure has stripped away its outer atmosphere. Expelled material is being very strongly excited by hard UV, producing abundant glow in OIII (blue). There is also a surprising amount of NII (green) which is normally found in strongly excited but tenuous gas dredged from the depths. H-alpha (red) maps the location of denser material. The topographical separation of these three components was very strong, resulting in a naturally very saturated picture. Seeing was unusually good and we have not deconvolved the image.

We have consciously departed from our usual "kermit-and-violet" idiom here, aiming to produce an overall measured-to-be-neutral colour balance and white stars.

Grown-ups are invited to compare this image with Bernini's sculpture of Pluto and Persephone at the Villa Borghese outside Rome. There are some resemblances in the lower half of this image to Pluto's muscular arms, and a general feeling of turbulent excess of emotion.

A 2megabyte 1:1 version is here (http://www.mikeberthonjones.smugmug.com/Category/Wolf-Rayet/i-9tMXf9D/0/O/Thor%27s%20Helmet%20Red%20Ha%20Gree n%20NII%20Blue%20OIII%206hrs%20each .jpg)

Best,
Mike n Trish

[RickS]

Great details, Mike, and the use of NII adds an extra dimension.

Cheers,
Rick.

[BruceG]

Simply stunning!
Bruce.

[alpal]

Hi Mike & Trish,
I like that - fantastic data.
I think it would look better if the Red & Green channels were swapped -
it would make it look more blue.
Also if the black point was raised it would show the darker areas better.
The black is a bit clipped.

cheers
Allan

[Andy01]

Wow - that's one spooky, haunted house colour palate - very X-Files, love the way you keep pushing established boundaries :thumbsup: :)

[Bassnut]

Mike n Trish. WHAT are you thinking :P !. Exactly as Allan says, swap red and green (nothing else) and its fantastic :eyepop:. And monster detail!, deep!, excellent..

A classic, very very well done. Swapped here for big (http://fredsastro.smugmug.com/Temp/n-CvvjD/i-ZNjcsmH/A)

[Rod771]

Fantastic image and great info , very enjoyable! My wife loves the purple , I prefer the colour swapped image but that's just down to one's taste. Lovely detail. Well done! :thumbsup:

[Placidus]

Thanks, Rick. Thor was very Spartan with the SII, and that prompted us to try NII.



Thanks much Bruce !



Cheers, Alan, glad you like it. Swapping red and green would make it Hubble convention. NII is two nM longer than Ha. But as Norman Lindsay famously said, "the art is at a maximum at the moment of greatest resistance from the medium." You're right that there is a tiny bit of clipping in the deepest dust lanes.



Yippee !!! Thanks, mate!



Big hug, Fred! The original motivation for NII to green was to minimize the famous Kermit look. Let's pretend your version is the official one. We hope to get more data on this one, to remove some of the grit in the faintest stuff, so perhaps the next version will be red-green reversed.

Best,
Mike n Trish

[Placidus]

By unanimous popular demand, here is Thor in Hubble Palette. Red: NII, Green: H-alpha, Blue: OIII, all 6hrs each. Big one here. (http://www.mikeberthonjones.smugmug.com/Category/Wolf-Rayet/i-8DCRS38/0/O/Thor%20Hubble%20Palette.jpg) I did kinda like the other one. :sadeyes: It was more eye-catching.

[marc4darkskies]

Ah yes - lovely shot Mike - great depth & detail! :thumbsup: And I also prefer Fred's palette.

Cheers, Marcus

[alpal]

Hi Mike,
much better.
Now if you raised the black point?

cheers
Allan

[Stevec35]

Very nice indeed! Why can't I do NB images that good?

Cheers

Steve

[gregbradley]

Nice detail. The red is very weak and needs a big boost as the colour spectrum is too biased for my taste.

Greg.

[Placidus]

Thanks, Marcus. Getting there.



Thanks, Allan. Should it clear up again, I'll try adding much more data and then produce a version with more subtle faint detail.



Thanks, Steve. I'm very happy with the sharpness and (for a quick 18 hour exposure) the depth is ok. The colour seems to need some more thought.

[Slawomir]

Beautiful image Mike, and I much prefer the second version :)

Would you consider a minor cosmetic correction to eliminate two colour (green and purple) artefacts from hot pixels right in the middle of the image?

[Placidus]

Hi, Greg,

Thanks for your useful comments. I'm pleased with the detail. It's much sharper than my effort from a few years ago. I accept completely that your aesthetic preference would be for Thor to be redder. My reason for not doing this:

The image as a whole is colour neutral. The raw 16 bit RGB values are 5021:5145:5221 out of 65535, which is within a fraction of a percent of colour neutral. But compared with the universe as a whole, Thor has much more OIII than H-alpha, and far more of that than NII. So ignoring aesthetics, in Hubble palette, Thor should appear blue-green compared with the image as a whole.

I guess I could lean a little toward Thor being slightly less blue-green, as a compromise between aesthetics and not having every object look the same. I'll keep that in mind for the mega-data version if it ever happens.

Warmest regards, and thanks for putting up with my lengthy explanation.
Mike

[gregbradley]

Hi Mike,

This is a really nice object. With narrowband of course its eye of beholder, so no right/wrong here.

One of my personal favourites of my own images was of this last year;

http://www.pbase.com/gregbradley/image/156159484

There are some nice ridges of reddish nebula in amongst the O111 areas.

Adam Block has a spectacular image of it. Astrodon narrowband tutorial is very good in this regard as it gives you control over the colours as Ha is often mapped to green, green can take over easily.

Greg.

[Placidus]

Greg, your image is beautiful. Adam Block's just makes one want to weep. I see what you mean about the streak of red along the wing of the helmet on our right. Can you give me a link to what scope, exposure, and mapping Adam used?

[gregbradley]

Adam often uses a 24 inch RCOS. I think now its a 32 inch Schulman which I think is an RC.

As far as exposure lengths go - not sure if its not on the image. He images at Mount Lemmon observatory so he's also on a mountain top!

Greg.

[Placidus]

Thanks, Greg. A mountain is a top bit of kit.

[Paul Haese]

Mike, I like your latest rendition. Though maybe just us some HSLV green to remove the green in the yellow stars. Much more pleasing palette. Detail looks great. I would like a 20" but it might require a big shortening of the pier. Nice light bucket you have there.

[strongmanmike]

Wow and wow to both of you :)

Mike that's some awesome big scope (arhem, I want your scope) work, love it :thumbsup:...colour?..meah?? it's better in the second one for sure but bit of star egging but the scale and grandeur more than makes up for it, good job, enjoyable view :thumbsup:

Greg...man, your best image with the 17" I recon :thumbsup:

Mike

[alpal]

Mike,
I couldn't wait that long -
I think we can get a sneak preview now.
I hope you don't mind?
I raised the black point & did a little bit of further processing.
See here in the staging area of Astrobin - not published.

http://www.astrobin.com/149767/0/


cheers
Allan

[Placidus]

Cheers, Slawomir!



Thanks muchly, Paul. I'm really valuing your advice and will take into account next time round.



Thanks, Mike. Grandeur sounds good! Will add eggy stars to the to-do list.



Wow, Allan, that worked! Thanks!

Thanks to everyone for the useful pointers.
Best,
Mike

[alpal]

Mike,
Thanks Mike.
With more data & no clipping of the black it could be an APOD.
Even more magic could be created by working with a starless version &
shoving RGB stars back in later.
I can only dream of working with such wonderful data of my own.

cheers
Allan

[Andy01]

Al you've excelled yourself with that processing result, and now you and Mike have inspired me to add that puppy to my list of targets!
Well done :)
Andy

[Ross G]

Hi Mike,

What an amazing photo!

Great detail, so sharp and well composed.

A "standout" photo of this object

Ross.

[multiweb]

Awesome shot Mike. High-res show superb details with a great image scale. Another one for the future pool room. :thumbsup::thumbsup::thumbsup:

[Placidus]

Thanks muchly Ross, glad you like it.



Thanks Marc, Yippee!