Hi All,
It’s been a while between images, though still actively imaging, output has been slow. I’d like to present an image in which I’ve been working on for a while. I previously imaged this target before but at a much longer focal length. I’m pleased to revisit the area with a shorter focal length instrument to portray the majestic nature of the scene. Anyway, here it is; Mandel-Wilson 9 (MW9) – Integrated Flux Nebula (IFN) in Apus. Warning: large resolution images may take some time to load.
About the target;
Mandel-Wilson 9 (MW9) is the result of the ongoing search for unexplored nebulae surrounding the very high and low galactic latitudes. Known as Integrated Flux Nebula (IFN), it’s illuminated not by a single star, but by the energy from the integrated flux of all the stars in the Milky Way. These nebulae clouds, an important component of the Interstellar Medium, are composed of dust particles, hydrogen, carbon monoxide and other elements. Nestled amongst this vast, yet faint nebulosity is the spiral galaxy IC4633. Reference
About the image;
The image is a six panel LRGB mosaic covering a 6.2 degree square field of view. I used a synthetic luminance to boost the relatively short luminance filtered data S/N. As seen, it’s not been the easiest data to work with given a couple of the nights were heavily compounded by smoke from control burns that occurred sometime back (22/04). While I acquired the data when the target was high, the smoke haze resulted in diffused stellar profiles and halos in which I was partly able to address through selective processing. In some instances however, I needed to re-acquired data as the masters were ghastly and complex to match between frames. I estimate I threw out around 3 hours of data due to this. Interestingly, the blue filtered data was extremely weak across the frames. Other than the O, B and A spec. type stars and the subtle blue reflection nebulosity, the area is mostly void of any blue hues in the IFN. This was rather troublesome resulting in the need to use pixel math to reach a desirable channel balance. Apologies - no accurate G2V here; really “whacked out” in my opinion which I’m not overly pleased about. However, I’m willing to accept this as colour fidelity is compromised when trying to match colours between mosaic panels. A single frame image is trivial in comparison. Perhaps the most frustrating part of producing this image was panel rotation. I set the PA to 251 degrees for the correct framing as per the mosaic plan in TheSky, yet two frames didn’t overlap which resulted in a star void triangle almost center of the image. Arrggg! Back to the scope to acquire more data. I attribute this to two items; bad planning i.e. image overlap was rather tight at 5% as I was attempting to maximise the FOV. A higher overlap percentage is a sacrifice, but probably best to be cautious. In addition, I failed to adhere to golden rule of aligning northern parts of the frames if the target is south of the celestial equator to ensure sufficient overlap. The opposite is true for northern targets. Will pay more attention to TheSky mosaic plan in future. I’ve found adherence to this rule is not a problem for targets close to the celestial equator or imaging at longer focal lengths as noticeable rotation is usually to a minimum for both situations. Rotation appears quicker closer to pole. With the pain/negative comments out the way, I have to say that this was an enjoyable challenge in which I suspect will fuel similar projects.
No surprises on the processing side so will keep it short calibration (dark/bias/flats), hot/dead pixel removal, subs registered and combined in CCDStack. With the lum masters created, they were loaded into Registar to precisely align the panels for the mosaic. The lum master panels were then loaded into MaximDL for a mild DDP stretch to aid in keeping the same brightness/contrast across the frames. Not perfect, but reduces the workload. I don’t heavily DDP stretch the frames, just a subtle boost to manage the bit space. These were then loaded into PS as individual layers. Each panel was further stretch using level/curves along with the application of the brightness and contrast tool to match the illumination. At this point, any gradients present where manually removed in PS. There were a few, but didn’t pose too much of an issue. The panels were stitched together using layer masks to provide a smooth transition between them before being flattened. Didn't do a very good job of this in specific areas. The individual RGB combined panels went under similar treatment, but were registered directly with the stitched luminance instead of each other. The Integrated Flux Nebula is quite faint, marginally higher than the background ADU count. This required some additional stretching and masking to bring it out. I went for a natural colour saturation of the dusty IFN features. While it was very tempting to boost the saturation to extract a darker and richer tone, I found the result compounded the tonal differences of the nebulosity. It began to take on a mono-tone and featureless appearance. The presented image has been reduced by 50% in size and is a crop of a larger image - web friendly.
Anyway, sit back and have a swim around the scene. Not much in the way of background galaxies (a couple of PGCs and ICs) or other extended objects in this region, just a bucket load of stars, dust and errmm more dust. I particularly like the star (SAO 257486) nestled amongst the IFN producing blue reflection nebulosity. No idea if this is catalogued as I didn’t see it on any star charts during planning. Rather cool. Happy for someone to enlighten me with details.
Thanks for taking the time to read the blurp and/or check out the image. Hope you enjoyed it!
Cheers
Last edited by jase; 26-05-2009 at 08:39 PM.
Reason: Fixed up reference link
Once again, a masterful image, masterfully processed. I just love reading the way you go about capturing your data, and how you process it. It is always very insightful and I pick up something every time I read. Regardless of the fact that I'm still a DSLR newb.
Thanks, again.
Regards,
Humayun
Last edited by Octane; 26-05-2009 at 05:32 PM.
Reason: Spelling.
wow, the full res version fair pops out and really should be viewed to do the image justice. Masterfull stitching and processing Jase, I havent seen this object before (I think, certainly not this way). The colour is subtle and approriate.
The small view looks as if the background is too high, till you view the bigest one and realise its just due to the HUGE number of perfectly rendered stars.
Excellent work, a pleasure to view, so clean, so sharp.
Superb widefield Jase. Very dedicated work. It's interesting to know you use registar to align the mosaic panels. Do you then load the final in PS with photomerge? I recall you posting a close up (I think) of the galaxy at the end of the dust cloud. Wasn't it the pic you prepared for that gathering in the US last year?
Once again, a masterful image, masterfully processed. I just love reading the way you go about capturing your data, and how you process it. It is always very insightful and I pick up something every time I read. Regardless of the fact that I'm still a DSLR newb.
Thanks, again.
Regards,
Humayun
Thanks for the kind words Humayun. MW9 is well placed at the moment so would be interesting for others to give it a shot - especially those DSLR users. The nebulosity isn't Ha rich so in with a chance.
Quote:
Originally Posted by Bassnut
wow, the full res version fair pops out and really should be viewed to do the image justice. Masterfull stitching and processing Jase, I havent seen this object before (I think, certainly not this way). The colour is subtle and approriate.
The small view looks as if the background is too high, till you view the bigest one and realise its just due to the HUGE number of perfectly rendered stars.
Excellent work, a pleasure to view, so clean, so sharp.
Cheers Fred. Yes, the small 821x821 version does appear to have a high black point. Its actually not a different image, just the full size version resized to a lower resolution. As you indicate, the mass of stars probably provide this perspective. Pleased you liked it. Thanks for your comments.
Quote:
Originally Posted by multiweb
Superb widefield Jase. Very dedicated work. It's interesting to know you use registar to align the mosaic panels. Do you then load the final in PS with photomerge? I recall you posting a close up (I think) of the galaxy at the end of the dust cloud. Wasn't it the pic you prepared for that gathering in the US last year?
Thanks Marc. Registar
Seriously, its the best tool for mosaic registration. No, I don't use Photomerge, panel matching in brightness/contrast/colour is performed manually in PS. Gives the most control I've found. I've looked at a few PS plug-ins in an attempt to simplify the task, and they do, but not without compromise. Normally, I'd register against a wider field image to correct for frame rotation and the like, but finding a wide enough reference image of this area is ummm...non-existent. There are a few wide field shots around but didn't cover the same FOV I was working with. Yes, the longer focal length shot you're referring to can be seen here (heavily compounded by seeing conditions at the time - fat stars). Thanks for taking the time to check it out.
Magnificent Jase. Unheard of by me. The extent of work you go to, to achieve an image like this just leaves me in awe.
Always a pleasure to read your dialogue and view your images.
what can i say, only good stuff, its also nice seeing you shoot something thats not uber FL and with your own gear. keep the old hand in so the scope dont rust over.
browsed your website recently, stuff there i hadnt seen here, although i did take a month or two off so might have missed them. will find the orion mosaic usefull once it returns, gives me ideas for future targets.
Cheers Steven. A change of scenery never hurts. Pleased you liked it.
Quote:
Originally Posted by seeker372011
fantastic shot of an object I had never heard of before.
appears to be worth every bit of the effort that went into producing it I might add
Narayan
Thanks for checking out the image Narayan. The image blog may sound like quite some work went into it, but in reality it wasn't too much. The work would have been ten-fold if the data had major gradients. Obviously, it helps to acquire the data from dark skies as has been done here to minimise them. However, even from the darkest of skies you'll still have gradients, be it subtle. Its just something to learn to deal with. Thanks again.
Quote:
Originally Posted by Hagar
Magnificent Jase. Unheard of by me. The extent of work you go to, to achieve an image like this just leaves me in awe.
Always a pleasure to read your dialogue and view your images.
Cheers Doug. Mosaics are all in the planning. I just sit around during the data acquisition as frame centering, focusing etc is automated. Sometimes I get out the binos and have a squiz around to fill in time. I'm so not a visual astronomer (clearly given the only eye piece I own is an illuminated reticle used for guiding should the CCD camera fail me!). Something I learnt during this process is that I need to fine tune my operations in PS. At one point, the PSD file reached over 3.2Gb in size due to the different layers and masks. Rather ridiculous. I think breaking the mosaic up further would assist. Anyway, pleased you liked it. Thanks for your comments.
Quote:
Originally Posted by Tamtarn
A pleasure to browse around Jase. Everything is blended beautifully. A rarely imaged region by all accounts. Thanks for posting
Thanks Barb and David. The full res makes a nice print. Other than the dust, its a rather featureless area. Still quite interesting however. Thanks again.
Quote:
Originally Posted by Alchemy
what can i say, only good stuff, its also nice seeing you shoot something thats not uber FL and with your own gear. keep the old hand in so the scope dont rust over.
browsed your website recently, stuff there i hadnt seen here, although i did take a month or two off so might have missed them. will find the orion mosaic usefull once it returns, gives me ideas for future targets.
Cheers Clive. Still have the long FL bug, using my own rig just breaks up the monotony providing an alternate challenge. Processing wide field data is different to that of heavily oversampled data. Still have a couple of Lightbuckets images yet to process. Time has been my biggest enemy of late, not data - got plenty of that. Yes, a couple of images on the site which I haven't posted here. I usually post most of the work, but not all. Tear drop nebula is a classic example. Crap data due to reflections, but given no-one has imaged it at 4.8m FL and probably never will given its a tough target with its proximity to bright stars, I thought I'd upload it being rather unique. Given its an image that I would consider as "crap", I don't draw attention to it. Interestingly, its receives quite a few web hits. Anyway, thanks for taking the time to check it out and comment.
Not bad at all Jase. That faint dust is most probably masked by the light pollution at my place. Next time you need a good rectilinear widefield give me a pm and if I can see it from my place I will whip one up. The Canon 300mm F2.8L lens has a field of 7x4.6 degrees with a full frame and has far less than 1% rectilinear distortion over its entire field.
Have you tried the the calibrate function in Registar? With enough overlap it matches brightness and colour balance etc.
Jase the other thing you can do is generate a map and register with Registar to the map. I produced a map with a 10 degree FOV with Star Atlas Pro and used Registar to superimpose your image. It helps if you turn off the clutter of labels etc. Since your optic is rectilinear you can see that the map is as well. I left the galaxies turned on for all you galaxy hunters.
Registar
