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.
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.
Mike n Trish. WHAT are you thinking !. Exactly as Allan says, swap red and green (nothing else) and its fantastic . And monster detail!, deep!, excellent..
A classic, very very well done. Swapped here for big
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!
Great details, Mike, and the use of NII adds an extra dimension. Cheers, Rick.
Thanks, Rick. Thor was very Spartan with the SII, and that prompted us to try NII.
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Originally Posted by BruceG
Simply stunning! Bruce.
Thanks much Bruce !
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Originally Posted by 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
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.
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Originally Posted by Andy01
Wow - that's one spooky, haunted house colour palate - very X-Files, love the way you keep pushing established boundaries
Yippee !!! Thanks, mate!
Quote:
Originally Posted by Bassnut
Mike n Trish. WHAT are you thinking !. Exactly as Allan says, swap red and green (nothing else) and its fantastic . And monster detail!, deep!, excellent.A classic, very very well done. Swapped here for big
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.
By unanimous popular demand, here is Thor in Hubble Palette. Red: NII, Green: H-alpha, Blue: OIII, all 6hrs each. Big one here. I did kinda like the other one. It was more eye-catching.
Nice detail. The red is very weak and needs a big boost as the colour spectrum is too biased for my taste.
Greg.
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
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, 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?
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?
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!
!. Exactly as Allan says, swap red and green (nothing else) and its fantastic 
. And monster detail!, deep!, excellent..
It was more eye-catching.
