A bubble within a bubble

[gregbradley]

Bubble, bubble, double trouble.

SH2 308 (Sharpless Catalogue) is a large bubble mostly in O3. I was inspired to image this object from Marco's original image of it which is probably the definitive image of this object.

Using the Trius 694 with its something like 66% QE in O3 (the highest of any sensor) I thought I would have a go at it. The Honders tends to do those big halos on really bright stars but I actually don't mind that as it really shows this star is a monster. Like an old Mt Palomar photo.

I almost did not get anywhere as my S11 and O111 filters were mislabelled as each other and it does not show up in S11. So at first I could not find it. I suspected something was amiss when I was clearly identifying the star patterns surrounding it yet nothing was showing up in a 30 second framing shot.

It shows up somewhat in Ha but dimly. I am happy that the Honders picked up so much Ha as I have not seen this much in other images. There definitely seems to be a Ha bubble behind the main O3 bubble.

Its a large object and really could do with a larger sensor on this one but that's what was on the scope and getting everything tilt free is a bit of a procedure so....

http://www.pbase.com/gregbradley/image/162575405/large regular size
http://www.pbase.com/gregbradley/image/162575405/original Larger size

O3 Ha LRGB image.

Greg.

[Atmos]

The bubble itself looks nice and clean... Many of the stars look a bit funky. There are a couple down towards the bottom of the image that have blue/yellowish rings around them (think Saturn kind of rings).
Not sure what's causing it, artefact of different seeing conditions between LRGB and narrowband?

[E_ri_k]

Hey Greg, nice image! I like the halo too. It's a shame you couldn't fit it all in on the sensor, although I like the framing. Nice detail and colour.
Erik

[Placidus]

Hi, Greg,

Very sharp and clean as usual. Lovely job.

Like us, you found an almost perfect match between the distributions of the H-alpha and [OIII]. (There are just a couple tiny patches where the relative contribution of H-alpha is a bit higher than elsewhere)

That is encouraging from the scientific accuracy point of view, but also interesting in that it seems almost unique up there. We could have fun trying to guess why. Gives the image a very special and unusual look, like an ice sculpture.

Cheers,
MnT

[Bassnut]

Thats excellent Greg, a cracker!. Smooth and detailed. I dont know why, but I laughed when I saw the large size, it was quite suprise, right out of left field and very impressive.

[gregbradley]

Probably an imperfect star mask fit on the O3. I fixed an imperfect star mask for the Ha that was making dark halos around a lot of stars. I saw a few minor star defects and didn't think they were that bad but yeah I should tweak that O3 star mask a bit more.



Thanks Erik. The small size of the 694 sensor meant it won't all fit. I can swap over to the 16803 and then it would be too large! 16803 would frame it all easily. Next year. I just got my 694 perfectly tilt free so I am scared to touch it!



It looks a lot like someone blowing a soap bubble with the Porpoise type snout at one end (not fully shown in my image). I tried to make the O3 more teal rather than straight blue. There is a lot of detail in the O3 subs that did not quite make it through in the final image. I should post the O3 by itself and you can see. It shows lots of filaments and strands.



Thanks Fred. Its quite an impressive object and not often imaged. I am glad I was able to find it after trying for about an hour simply to locate it!
The little Trius is really super sensitive in O3 so that is one reason I wanted to have a go at it.

Greg.

[Slawomir]

Looks very impressive Greg!

On a technical side, it seems that flats have not been applied, is that right? Or maybe I am seeing amp glow around the edges? Those brighter areas on the left, right and top of the image...:question: ...darks should fix it if that is the case.

[gregbradley]

I fixed this. Its better now, maybe not perfect but not bad.

[Atmos]

Looks a lot better! :thumbsup:

[marc4darkskies]

Nice image Greg! :thumbsup: Shame it didn't all fit into the FOV!

[RickS]

Fantastic detail, especially in the Ha, Greg. Have you seen Don Goldman's 2009 APOD image? It shows most of the same features but yours is cleaner, more detailed and shows the Ha much more clearly.

Cheers,
Rick.

[gregbradley]

'

I started not using darks as they were showing up the pattern noise of the sensor - the microlens array. But yeah there is some amp glow there. I applied a dark in an unusual way but its fixed the amp glow now. Thanks for that. A bright left hand edge from a bias was already cropped out so it was just the amp glow. I'll start a thread about this pattern noise because its a pain.



Cheers.



Yeah. KAF16200 is on the wishlist or I can simply whack on the Proline and get it in easily but lose a lot of O3 sensitivity.

Greg.

[Geoff45]

Beautifully done on a very interesting object Greg. Colours and detail are top notch.
Geoff

[topheart]

Good on you Greg....now it's time for a bubble mosaic!!

Cheers,
Tim

[gregbradley]

Thanks Geoff. I was happy with the data coming down.



Bubble Mosaics. Its sounds like a Patent Pending Process!

Greg.

[rustigsmed]

very nice greg! i would be tempted to turn it upside down to get the dolphin view, loving the mix of O3 and Ha!

[Thacphan]

Great work Greg
Tom

[Andy01]

Only one thing wrong with that picture Greg, it's so good we want to see more of it!
Cheers
Andy

[gregbradley]

Thanks Rick. That is quite a compliment coming from someone of your standards.

Greg.

[gregbradley]

Thanks. Yes I suppose that could work. It looks to me like someone blowing a bubble.



Thanks Tom.



Thanks Andy, nice of you to say. Perhaps I should put the Proline on and do another widefield version whilst its still around.

Greg.

[strongmanmike]

I agree with Russell :D

Looking good Greg, it is a rather intriguing object :thumbsup:

Mike

[gregbradley]

Yes it does look good upside down. I may change it.

Its a very large bubble as well. Its really a target for the Proline.

Greg.

[Stevec35]

Very nice rendition of this obviously difficult object Greg. The colour does bother me a bit as it seems a bit too magenta but I've never seen a shot of it before so maybe this is what it should look like.

Cheers

Steve

[gregbradley]

Thanks Steve. The magenta is the Ha component which is much deeper than what I have seen in other's images which usually only show the blue O3.

Greg.

[Shiraz]

that is a cracker of an image Greg - smooth, detailed and delicate.

one of your best.

[gregbradley]

Gee thanks Ray. I appreciate it.

Greg.

[multiweb]

That's really good Greg. Looks like and ESO shot. :thumbsup::thumbsup::thumbsup:

[Regulus]

I'm a bit speechless mate. Very well done. A beautiful image to look at.

Trev

[Fabiomax]

What a great job! I think it is very weak, I have not seen so many pictures of this nebula like this.

Cheers,

Fabiomax

[Leonardo70]

Wonderful Greg ... congrats !

All the best,
Leo

[marco]

Good one Greg! You got lots of Ha in your image and also the details are very very good, despite the stars that looks not perfectly round. I am surprised by your O3 data though, with 260m @ f/3.8 you should have much more signal IMHO..
About the reflections, I had similar problems in the past and their were caused by the CCD camera windows reflecting back and forth with the filters. When I had the window replaced by FLI with a new low reflective window during last camera maintenance they disappeared. I would check if perhaps SLX offers the same replacement with a broadband multicoated low reflective windows surface. Your telescope is fast and collect lots of light, the sensor is also very high QE so a small percentage of light reflected is easily recorded..
Ciao
Marco

[gregbradley]

Thanks Marc.:thumbsup:



Thank you Trev. I appreciate that.



Its not that commonly imaged. Perhaps its because it is so dim.



Grazie Leo.



Thanks Marco. The O111 data is very detailed. Some of that detail seem to diminish during the blend. I will have to look at a possible repro to regain some of that detail. Also there are processing choices in this image. I could easily have made it an all blue type image as it will go there easily. But I wanted more colour balance and the Ha seemed surprisingly detailed hence the more balanced approach that sacrificised some of the O111 detail for better balance.

Thanks for the tip about the reflections. That may be the case although other images I have seen from users of the RHA show similar with very bright stars.

Greg.

[Decimus]

An unbelievably beautiful image, Greg. Simply stunning! :eyepop:

[gregbradley]

Thanks very much Richard. High praise!

Greg.