RCW120 -Dollar Sign Nebula

[jase]

Hi all,

Long time no image post! I've started to go over a few wide field images I had previously taken and targeting interesting features at a longer focal length. Am always up for a project steering away from the mainstream targets. There are several other targets on the list (weather and season permitting), including some around the scp which will be a challenge as they don't get much altitude and likely require mega data. Will still be fun trying though...

Anyway here's my rendition of RCW120 (http://cosmicphotos.com/gallery/image.php?fld_image_id=248&fld_album_id=11)

The wide field image that prompted my return to the area can be seen here (http://cosmicphotos.com/gallery/image.php?fld_image_id=240&fld_album_id=11) providing a perspective of where the nebula resides in comparison to other key HII objects.

Perhaps the nebula should be known as the "Dollar Sign Nebula" given its structure. With a SHO palette I could even make it look green. Who wants to be in the red anyway? :P

About the scene
RCW 120 (aka Sh 2-3, Gum 58) is a HII emission nebula residing in the constellation Scorpius. The nebula is an expanding star forming cloud of ionised gas powered by a central star. The star's radiation interacts with the surrounding dust and gas, increasing the density of matter in new locations, triggering a fresh round of starbirth. RCW 120 is about ten light-years across, is located approximately 4,300 light-years away.

About the image
This is the first light image for the new set up, well not really new. Still the PME and Alta F16M but the scope is a 12.5" RCOS w/TCC2. Has taken considerable time and energy to get the system up and running with most of time spent on being meticulous with collimation. The 16803 seems to be the limit for the 70mm optical train. Still some additional work to be done it fine tuning the automated sky flat acquisition but it works ok for now, just not as efficient as it could be with the PIR in operation. I was without a guider for this image (needed servicing, thanks Peter for the repairs) but I decided to press on regardless with the clear weather about. Didn't seem to make too much of a difference with the broadband data, nice round stars. The PME is well polar aligned and a 300 point tpoint model with protrack enabled, getting 900sec unguided subs is a reality. I began to get minor star elongation at 1200s subs which some would still see as acceptable, but I wasn't happy. 900s is not long enough for narrow band data as this image shows. I had to result to noise reduction through object masking. It requires significantly more exposure time to pack more punch. Processed in MaximDL (Ha pixel math), CCDStack and Photoshop CS5. Usual workflow for [Ha+R]GB data with Ha data added to both red and blue channels - 80% Red, 15% blue works for me. All acquired 1x1, Ha 6hrs, RGB 3hrs each for a total of 15hrs.

Hope you like it! All comments welcome.

Cheers

[Larryp]

Very nice!

[seeker372011]

Very nice. Don't quite see the $ but more of a rubber ducky to me :)

Not of course a commonly imaged target so all the better to see

Thanks for sharing

PS I wish I had some way to go 900 secs without auto guiding !let alone 1200

[jase]

Cheers Larry!



Thanks Narayan. Yes, like most target names, some require imagination to see. You are right that it does look rubber duck like. Perhaps the theme of July is ducks or duck season. :) Thanks for taking the time to check it out.

[Paul Haese]

Like you Jase; I am a mega data convert. Nice setup by the sounds of it but I can understand sorting issues.

Really interesting looking object and will have to look around that area to attend to a few objects worth my consideration.

[Stevec35]

Nice shot Jase! Have to say I can't see a dollar sign though.

Cheers

Steve

[jase]

Thanks Paul. Set up has taken a while, thats for sure. I followed the information from Brad Moore's 2010 AIC (http://www.aicccd.com/archive/2010_presentation_archive.html) presentation (Optimizing your Imaging Train) to 'hyper-tune' the system, in particular mount (pec,tpoint,balance) and collimation info. Good information that comes from experience. As mentioned in the original post, I spent considerable time on collimation. The Tak collimation scope only got me 85% there. Probably good enough but I wanted more. I like the method he suggests in MaximDL for even distribution of energy. Also, I had considerable effort in balancing the scope. Despite pier modifications, its a tight fit in the 2.3m Sirius dome, so I needed to set the OTA well back on the PME dovetail and use counter weights to balance in DEC. Its all come together relatively well. I'd say I'm where I want to be, limited by the seeing as opposed to the equipment... AO will likely be the next evolution of the set up but I'm in no rush at this point.



Thanks Steve. Pleased you liked it. :thumbsup:

[iceman]

Nice image Jase! Could be a Superman symbol? :)

Welcome back!

[SkyViking]

A beautiful nebula and excellent image Jase, nicely done.
900s unguided sounds like a dream, it must be great to have your setup running so well!
I'm upgrading to a 12.5" soon so I'll be tinkering with my own setup for a while I imagine.

[Octane]

Mate, it is so, so, so, so, so good seeing a new image from you. I thought we'd lost you to the astro doldrums. :)

This is speccy. I can see the dollar sign easily. :)

Looking forward to your next installment. :)

H

[jase]

Cheers Mike. :) Does look like the superman symbol! :lol: Hadn't thought of that one. When you spend hours processing an image, your mind starts to play tricks on you. I think I came back to this image with fresh eyes around three or four times, but each time I continued to see the dollar sign. I'm probably just nuts :screwy:



Thank you kindly Rolf! What you put in is what you get out, as you and others well know. Tweaks do take time but its worth the effort. I wanted to keep guider corrections down to a minimum so being able to go unguided for long sub durations was important. Improvements in PEC were moderate (PME is already low), but most of the gain comes from Protrack with unguided operations. Looking forward to seeing some of your images with the 12.5". Uber data collection awaits... :) Thanks again for checking out the image.



Cheers H! :) Yes, it has been a long time coming. Not quite back in full effect, but progressively getting back into it. With most of the equipment issues addressed, I can now focus on the more fun side of imaging, that is processing data. Thanks for taking a look and making comment.

[rustigsmed]

Looks great Jase, thanks for sharing!

glad to hear imaging system is coming together!

[leon]

It has been a while Jase, but you sure come back with a bang, superb image indeed, 15 hours, wow !!

Yes, the dollar sign is pretty easy to pick, well done.

Leon

[jase]

Cheers Rusty. Pleased you liked it. :thumbsup:



Thanks Leon! :) Good to hear from you mate. I'll try not to make it so long next time. Thanks for checking it out! :thumbsup:

[RickS]

Interesting little neb, Jase. Nice to see it in situ in the wide field as well. An impressive feat without guiding!

Cheers,
Rick.

[jase]

Thanks Rick. Something different, that's for sure. Am looking forward to guided images again. Alas I've not yet had the time to work through ACP's rotated guiding configuration, but I'm keen to do so promptly as there is no way I'm going to recalibrate the guider every time the instrument rotator changes position angle. Its simply not an option across multiple targets at different PAs in an automated data acquisition process. Good news is that it looks easy to set up, just need some clear skies to configure and test on a few targets. Thanks again! :)

[atalas]

Nice to see a new image from you Jase!looks great,well done of cause.

[multiweb]

Nice one Jase. More data will make it smoother. Good to see you back into it with your new rig. :thumbsup:

[Ross G]

Great looking photo Jase.

I love the colour and composition.

Good luck with the new equipment.


Ross.

[strongmanmike]

Yeh it's a very nice shot Jase with plenty of your usual quality elements.

Cool how you were prompted to shoot it too, your very own Palomar Schmidt-200" Hale combo :thumbsup:

Actually your wide field version prompted me to shoot part of it (http://www.pbase.com/strongmanmike2002/image/143429323/large) with the AG12 and 16803 last year also :thumbsup:

Mike

[ChrisM]

Nice result Jase. I haven't seen this DSO previously.
Chris

[dvj]

Exceptional image. I've been hoping to see someone shoot this one with longer focal length.

j

[Peter Ward]

I'd suggest many deep sky wannabes take a good long look at this master class of an image.

Superbly done Jase. :thumbsup:

[marc4darkskies]

Good to see you back Jase! Lovely image!

Cheers, Marcus

[jase]

Thanks Louie. :) A little rusty on some aspects of processing but a pleasing result none the less. Thanks for checking it out.



Cheers Marc. :thumbsup: For sure, more data would go a long way. I did collect close to 19hrs but dumped the bad subs with FWHM being too high. I'm not entirely certain of the local conditions yet when it comes to seeing. Thanks again!



Thank you kindly Ross. :) Need all the luck I can get, let me tell you. Down time due to equipment troubles is plain frustrating, tweaking performance less so, but in the end I'm pleased to be able to get a result to share. There comes a point that the endless tweaks provide diminishing returns that for sure. Anyway, I'm pleased you enjoyed it. Thanks!



Cheers Mike! :thumbsup: Yes its good to go back over previous images to reshoot something else in the frame or for that matter try a different palette. I used the wide field image as an overly in TheSky to ensure I obtained the composition I wanted. I've had a few comments that composition could have been better with RCW120 centered but its not what I wanted. The star field to the lower left and Ha nebulosity to the lower right adds an extra dimension in my opinion. Nice work on NGC6281 too. Its a great FoV. Thanks for checking it out.



Thanks Chris! Yes, I'm surprised by the lack of amateur images of this target. I saw one from ESO using a multiband palette of IR? and visible wavelengths that really brought out the bubble like structure around the brighter HII area. It's only seen as faint Ha data in this image and is poorly defined. Thanks for your comment. :)



Cheers John! :) Pleased you liked it! Its an intriguing nebula at short focal lengths. I recall when I started to process RCW119 wide field image I wanted to know more. To get an up close perspective with the interesting dark nebulosity rift zig-zagging through the HII. I now look back at some of the wide field images I've taken as galactic road maps showing different features urging for more focal length. Too many targets, not enough time. I'm sure we all face this dilemma!



Thanks Peter! You're an old hand at these focal lengths so I appreciate the tip of the hat. :)



Thanks Marcus! :thumbsup: Indeed good to be back. As they say, you're only as good as your last image. Keen to see what you'll nail with your new set up too.

====
Thanks all. Appreciate the support. :)

[RobF]

Great going Jase, and like many others, SO happy to see you still working and posting your astrophotography! :thumbsup:

[Shiraz]

gosh that is a classy image Jase - exceptional. regards Ray

[jase]

Cheers Rob! :) It was only a matter of time before I got back into. Once bitten by the imaging bug, its with you for life. This form of technical art is addictive. Ideally I wanted to start fresh with new kit hence the big sell up but I decided to work with what I had on hand. Thanks for checking out the image and making comment.



Pleased you liked it, Ray. I hope this image sparks interest in others to try it. I suspect it would look quite different in narrowband or even those thrill seekers who venture the near infrared path. Thanks again.

[E_ri_k]

Great image Jase! That wide field shot is fantastic, so much going on there! Nice comparison with the wide field and the closeup.
Erik

[h0ughy]

worth the wait! thank you for the photon vista

[tilbrook@rbe.ne]

Superb Jase!!

Such a beautiful field and that dollar sign sure stands out!

Cheers,

Justin.

[jase]

Cheers Erik. :) Indeed the wide field image provides an interesting perspective. For a further extension of the FoV, you can see RCW119 (aka Gum57) in the top left corner of a different image I produced as shown labelled here (http://cosmicphotos.com/reprocessed/ic4628_lbl.jpg). You can view larger resolutions of this scene here (http://cosmicphotos.com/gallery/image.php?fld_image_id=230&fld_album_id=11). Unfortunately, RCW120 is just out of the FoV. Probably one or two more mosaic panels would have done the trick. Thanks for checking out the images!



Thanks David! :thumbsup: This was somewhat a rags to riches image requiring additional processing than normal. Due to camera issues at the time, I experienced dark banding across the field related to bright stars (reference attached). The camera is currently being upgraded to the latest F-series board so should be back in action shortly. The banding issue was easy to deal with using layer masks. There are still some residual flaws related to this in the final image which I could have chased down and resolved for little gain. Thanks again.



Thanks Justin. Appreciated and pleased you liked it. :) The faint shell/bubble that surrounds the main HII structure sure is fascinating too.

===
Thanks again all. :D

[alpal]

I missed this thread.
That's a great image of a target I didn't know about.

[Leonardo70]

Wonderful image for me ...

Congrats,
Leo

[jase]

Thanks Allan! Apologies I didn't see your earlier reply to the post.:thanx: Am now embarrassed I didn't acknowledge earlier. Thanks for checking out the image.



Cheers Leo! Something new for you 'northerners' with a not so well known target. Actually is new for some southerners too. I'm pleased you liked it. :thumbsup:

[astronobob]

How awesome is that, Top Image ! Facinating with how much & now smooth the neb is you have :thumbsup:
Inspiring for the likes of myself to get a CCD quick ;)

[jase]

Thanks Bob. :) Pleased you enjoyed it. Don't hesitate on the CCD path, you will not regret it. You can always get your feet wet with a OSC first before diving off the top spring board with a Mono chip and filters.

[naskies]

Very nice, Jase. I really like the saturation.