A Cosmic Soap Bubble (Updated with more data and reprocessed)
Sharpless Sh 2-308 in O2HaRGB
8hrs O3 Astrodon 5nm 900 sec subs
3hrs O3 Astrodon 5nm 900 sec subs Binx2
2.5 hrs Ha Astrodon 5nm 900 sec subs
5x2min each RGB subs for the stars
Taken from my light polluted suburban Melbourne backyard over Four nights.
Damn but this things dim - like as in "Disaster Area" dim - (A spaceship painted black with a black interior with little black lights that light up black to let you know they're on) dim - to paraphrase Douglas Adams.
I've probably bitten off far more that my f5.6 gear can chew attempting this - but I'm kinda committed now. It's finally showing more detail and less noise but I suspect this object is ideally suited for the big boys to have a proper +40hr rendition. If memory serves, Marco did a beautiful rendition last year.
Neverless, here is my attempt with the data gathered thus far - comments welcome but given the circumstances and gear used, please be kind
Microscopic patch at the top of the bubble is burned out. Easy to fix if you felt heroic.
(In principle this truly wonderful beast would just exactly precisely NOT fit in my scope. I'd have to do a 4x4 mosaic.)
Well done.
Mike
Thanks Mike - and yes you're right about the burnout patch.
Maybe, just maybe I'll spend one more night on this beast at binx2 O3 only. Not sure about the law of diminishing returns as far as amount of data gathered vs. noise goes with this, maybe one of the experts can comment?
(In principle this truly wonderful beast would just exactly precisely NOT fit in my scope. I'd have to do a 4x4 mosaic.)
It fits perfectly in my FOV. If only I had a permanent observatory so I could image between the summer storms and clouds...
Quote:
Originally Posted by Andy01
Not sure about the law of diminishing returns as far as amount of data gathered vs. noise goes with this
Just considering shot noise, SNR improves with the square root of the total exposure time. If you have 4 hours and add another 4 then the SNR improves by approx 1.4 times. You doubled the time so the improvement is sqrt(2). If you added 12 hours to your 4 hours then the improvement would be 2 times. Just add 396 hours and your SNR will be 10 times better
Unfortunately, with narrowband you're almost certainly not shot noise limited so the improvement will be less than I suggest above.
.. Just add 396 hours and your SNR will be 10 times better Cheers, Rick.
(slits wrist).....
Lovely work so far Andy ..really is a beautiful and intriguing object this one, well done, not a biggy but maybe try and get the blue down in the background a bit?
Just considering shot noise, SNR improves with the square root of the total exposure time. If you have 4 hours and add another 4 then the SNR improves by approx 1.4 times. You doubled the time so the improvement is sqrt(2). If you added 12 hours to your 4 hours then the improvement would be 2 times. Just add 396 hours and your SNR will be 10 times better
Unfortunately, with narrowband you're almost certainly not shot noise limited so the improvement will be less than I suggest above.
Rick, I've done 8hrs O3 so far - if I added another 6 (and binned x2 as Greg suggested above - is that the same as 12 bin x1?) would that lead to a significant improvement in SNR?
Lovely work so far Andy ..really is a beautiful and intriguing object this one, well done, not a biggy but maybe try and get the blue down in the background a bit?
Thanks Mike - will do in the next version - assuming my sanity remains and I succeed in gathering some of those 396 hrs Rick recommended!
Hi Ross, thanks for taking the time to comment - I appreciate your positive feedback too, cheers!
Quote:
Originally Posted by Bassnut
Thats nuts, love it!, dark, forboding ,rich. Ballsy effort, 10 points for different. Somehow looks monster and sinister.
Cheers Fred, year there's definitely something spooky there - reminds me of "Tin Man" from the Star Trek TNG episode. Thanks for your feedback, reckon you should consider taking a 40+ hr crack at it next mate
One of my favourite targets - love it! I tried imaging one of the Sharpless "bubbles" myself once - even with a stack of 15 x 7 minute subs, it was BARELY discernible at full stretch!
You have rendered this one NICELY.
If you would ever like to post the FIT stacks, I would love to have a go - need to get back in the saddle and something to do during this damned cyclone!
One of my favourite targets - love it! I tried imaging one of the Sharpless "bubbles" myself once - even with a stack of 15 x 7 minute subs, it was BARELY discernible at full stretch!
You have rendered this one NICELY.
If you would ever like to post the FIT stacks, I would love to have a go - need to get back in the saddle and something to do during this damned cyclone!
Thanks Lewis, really appreciate your comments - yeah it's bloody feint! Maybe Mag 12? I really need at least f3.5 or wider to do it justice. I can just imagine the conversation with the wife now, "Honey, can I have...." lol
Bugger about the cyclone - I was raised in Gladstone so I feel for those folks up there, we used to have them all the time when i was a kid, scary too.
Incidentally, I met a guy at LMDSS last sat night with a nice Vixen refractor that he purchased from yourself - he's very happy with it too
Yes, Phil loves it, and so he should - every bit as good as a Tak fluorite! a WONDERFUL scope - I even asked to buy it back the other day I ended up getting my old Tak FC-100 instead, now updated somewhat (thanks Col!)
Anyway, if you care to share FITS, let me know - I'd love to have a go. I am tired of doing my own stuff again, and again, and again...
River almost over the road here... better pick the wife up in the 4WD
(slits wrist).....
