Hi All,
Long time, no post. Many factors came into play which restricted the amount of free time to pursue imaging, however all was not lost given I put valuable time into finally automating my observatory, thus data acquisition is now fully unattended. I’ve updated the equipment page with a couple pics if you’re interested, nothing exciting. With the freedom to collect data from a dark sky whenever I please (assuming its clear!), I expect I’ll be able to push myself to try a few tedious imaging projects. So to that end, I’d like to present one such initiative which in all honesty, I thought I’d never complete as I really should have started the data acquisition a couple of months earlier.
Anyway, here it is;
The small Sagittarius Star Cloud (M24).
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About the image
The image is a straight RGB composite consisting of three hours data per panel. A synthetic luminance was created to boost S/N in the fainter regions, but for the most part I opted to keep to the conventional RGB data where possible to minimise colour shifts. Panel overlap worked out ok - no requirement to go back to collect more data to fill in the “blanks”…a major relief let me tell you! I did however throw out approximately seven hours of poor data associated with high level clouds or dismal guiding (which I believe I’ve now resolved *sigh*). I utilised TheSky to create a scaffold image in which the panels were registered against prior to stitching to control rotation. The last three images I’ve produced with my gear have been mosaics; this one tallies as the fourth and let me tell you the processing doesn’t appear to be getting any easier. This has certainly been the most technically difficult image I’ve attempted to date. Dealing with neutral sky backgrounds seems to be easier than star clouds of our Milky Way. I actually thought the colour balance was significantly out on the center panels given they’re not the typical golden hues associated with the region. So I recombined the data over a few times, then realised what I originally produced was correct as the small Sagittarius Star cloud is quite a large object spanning 1.5 degrees (the equivalent of three full moons), but is partly obscured by dust, and contains predominately bright B through to F type stars. I was also under the impression that the swan was the same red hue as the eagle…how wrong was I! You learn something every day! Anyway, I do however feel colour fidelity has been lost in some regions due to the strict panel matching process. I’ll work on this technique with time through other projects. My Photoshop proficiency is rusty to say the least. In summary, the synth lum panels were created and stitched matching brightness and contrast between them. I then created the RGB and registered them against the stitched lum to ensure accurate alignment. Stitched the RGB panels matching colour balance and hue. Erased areas of the lum to ensure the straight RGB data filtered through, then flattened lum and RGB layer, then relayered again for colour enhancements. Colour boosting applied using a heavily DDP stretched and saturated RGB layer. Minor noise reduction and colour balance tweaks, seasoned to taste. Processed in MaximDL, CCDStack, Registar and Photoshop CS4. The presented image has been significantly reduced in size to make it web friendly.
Hope you enjoy the swim around this scene. I’ve attached TheSky mosaic plan for your reference. How bizarre, an image of the Eagle nebula, that actually looks like an eagle with its wings spread. Still think the Seagull nebula
IC2177 takes the prize however! …and what’s with the giant foot print that has stepped on M8, IC4685 and surrounds all about…
Thanks for checking it out. I’ll now disappear back into the shadows…
Cheers