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....
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?
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
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.
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.
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?
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.
Quote:
Originally Posted by 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
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!
Quote:
Originally Posted by 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)
Perhaps an error in the mask. I should check that.
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
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.
Quote:
Originally Posted by 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.
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.
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... ...darks should fix it if that is the case.
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?
I fixed this. Its better now, maybe not perfect but not bad.
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.
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... ...darks should fix it if that is the case.
'
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.
Quote:
Originally Posted by Atmos
Looks a lot better!
Cheers.
Quote:
Originally Posted by marc4darkskies
Nice image Greg! Shame it didn't all fit into the FOV!
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.
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.
Thanks Rick. That is quite a compliment coming from someone of your standards.
...darks should fix it if that is the case.
