NGC 246 Cetus Skull Nebula

[Placidus]

NGC 246 in Cetus is a reasonably large planetary nebula, about 4 min arc across. Magnitude about 8.5. Slightly brighter in OIII (blue) than in H-alpha (yellow). SII was insignificant, and we have not included any.

We've managed to resolve the mag 12 white dwarf separately from its somewhat brighter binary companion.

For the answer in the back of the book, see the stunning, jaw dropping, Gemini South shot. (http://www.gemini.edu/gallery/v/astronomical_images_and_illustratio ns/album04/ngc246_001.jpg.html)

According to the Gemini shot docco, the edge at the top of the frame is leading, creating a stronger shock as it hits interstellar medium, and that is why it is noticeably brighter than the bottom edge.

H-alpha 8hrs, OIII 8hrs, both in 1 hour unbinned subs. Field 11 min arc, 0.55 sec arc/pixel. Seeing was just under 2 sec arc.

Cheers,
Mike and Trish

Edit: Trish did a reprocess with H-alpha = red, OIII = turquoise, and slightly less noise reduction. I think it's better.
Mike

[Paul Haese]

That is an interesting looking object. Your resolution is quite similar in many respects to that of the Gemini image. I wonder what difference an AO would make to resolving the finer features with your scope.

[Stevec35]

A nice one once again Mike and Trish. I imaged this myself a few years back so perhaps it's time to do another one. Here's my effort:

Steve

http://members.pcug.org.au/~stevec/ngc246_STL11K_RC.htm

[RickS]

Nicely done, M&T! Great details for an object so small.

Cheers,
Rick.

[Placidus]

Thanks muchly Paul.

AO would be wonderful, but I suspect that finding a guide star would be very difficult at our focal length.



Thanks Steve. Looks like your shot even has an asteroid in it!



Thanks, Rick. The small size does tend to make it a target for the challenge and the joy, rather than for the beautiful final result.

Best,
Mike

[Paul Haese]

For the most part Mike, there are enough stars in the field of view to image at 1.7hz. Mag 10 stars can be seen at 0.5" with the 12" at 2430mm. When I imaged NGC253 I had a star which allowed 3.7hz or 0.2" guide exposures. Those so far seem rarer than stars at 0.5". Mind you I have only worked on collecting data on 3 objects so far. I am expecting that your superior light grasp would have a great ability to use dimmer stars despite the smaller field of view. There would be trade offs but I think your system would really benefit from an AO. I take your point though. Long FL has its issues.

[Placidus]

Wow! Thanks Paul. Perhaps it is something to investigate.

[AlexN]

Awesome image indeed.

Every time I see your images I wonder if I shouldn't cut back my gear collection and funnel a bit of money into itelescope ad get some data from a monster scope. That said I think the data is only a small piece of the puzzle and your superb processing skills make up the rest.


I will second Pauls assertion there. With my setup I was never unable to guide at at least 0.5sec guide exposures and the best I managed was 10hz

[gregbradley]

Nice image Mike.

I did a test O111 image and it was very dim. I should look at that again. So you got lots of O111 eh? Maybe my test image had some cloud at the time.

Greg.

[Shiraz]

Great image M&T - what an interesting object.

[Placidus]

Alex, you are too kind. Thanks for the encouragement! I'll certainly think about your and Paul's suggestions regarding adaptive optics.

Regarding hiring time on a big scope, whatever you do, don't stop having fun!




Thanks, Greg. Perhaps we should have said brighter in OIII than Ha, rather than bright in OIII. A 15 minute 3x3 binned SII shot showed absolutely nothing. Not a sausage.



Thanks, Ray.

[Placidus]

Trish did a reprocess mapping H-alpha to red, OIII to turquoise, and slightly less noise reduction. The fine wispy OIII stuff across the centre stands out better now.

[Bassnut]

Excellent Mike n Trish. Trish is now official colour balancer :thumbsup:. Youve also just given me my next project :D.

[Paul Haese]

Yeah I like that one better. Well done Trish.

[AlexN]

Given the field of view the detail in that is simply astonishing.

[gregbradley]

I like that also a lot better. Nice and natural Well done Trish.

I took some O111 last night. My original test shot obviously was blocked by cloud and I assumed there was nothing in O111 but as you say its almost as bright as the Ha.

Greg.

[rustigsmed]

awesome stuff M&T, glad to see that you have put your focal length onto a PN. utterly fascinating stuff.

all the best,
Russ

[Placidus]

Thanks, Fred. Looking forward to your version.



Cheers, Paul.



Thanks, Alex. No two PN's are the same. Would love to understand more about what makes them all so different. Binary companions, dust, actual planets, magnetic fields.



Thanks, Greg. Sounds like cloud was the explanation. Even thin stuff can do it.



Thanks Russ. Perhaps our grand theme is "things that go bump in the night", and PN's, WR's, SNR's etc fit that.


Best,
Mike

[strongmanmike]

Trish's latest rework looks good guys, PN's are all so individual in appearance, like our children...does anyone else see a round headed bloke with a comb-over hair style in this....:question:

Mike

[Placidus]

Kids and PN's: Agreed! And thanks!



Now I'm going to have to try really hard not to think of a cross between Wally from Dilbert and Michael Jackson. We used to see it as more like the face of a baby seal, but this year's data has wrecked that.

[astronobob]

Its Donald Trump :lol:
Fantastic work M & T ,,, I cant believe how close it is to the Gemini image :eyepop:
Great show of a beautifully interesting target, :thumbsup: :thumbsup:

[Placidus]

Thanks, Bob. We're tickled.

[SkyViking]

Very interesting and beautiful PN, and the processing is really nice especially the 2nd version. Great stuff!

[marc4darkskies]

Very impressive M&T! The second one definitely gets my vote!

[Placidus]

Cheers, Rolf. Thanks for the encouragement!



Thanks, Marcus. Glad you like it.