Hi All,
Still processing data from last new moon. I've got a couple more to go, but seem to not have had the time to work on them. Anyway, here's my latest effort;
IC443 - Jellyfish Nebula
About the target;
IC443 is a supernova remnant located in the constellation Gemini and is believed to have formed approximately 30,000 years ago due to a violent explosion of the star G189.6+3.3. The nebula's shape represents an expanding shell of gas scattered by strong interstellar winds from the explosion. IC443 is located 5,000 light-years away.
About the image;
Personally, I think this area is best suited to shorter focal lengths to pick up the long tendrils of the jellyfish, but always pleasing to see something different. The image is a LLRGB composite comprising of 4.5hrs (L:60min;R:70min;G:70min;B:70min). Not a huge amount of data, but of reasonable quality despite a few hiccups. The image is a hybrid containing data from both Lightbuckets 20" and 24" RCOS. The luminance was aquired on the 24", while RGB on the 20". The reasoning behind the hybrid was the 24" doesn't have the FOV of the STL11k attached to the 20". The 24" has the Apogee U42 which is an ultra sensitivity 2048x2048 sensor. So I used the RGB from the STL11k for the larger FOV and blended the 24" luminance over the top. Sounds relatively straight forward, but there where a few problems. Uncertain as to my mistake, but the MOAG missed the planned guide star on the 20" so the RGB is unguided. Huh? unguided at 4115mm FL is a testament to the PME's capabilities. This did however lead to sligh elongation of stars (as one would expect at such a focal length). I originally thought that this would destroy the data considering my original intention was to also use the RGB as a synthetic lum. However to circumvent the slight elongation I performed minor star shaping using a kernel filter in MaximDL. Elongation is still present but is considerably reduced. Some stars don't line up precisely result in colour finges, but these didn't both me too much so left them be. All other processing was conducted in CCDStack and PS4, both of which are relatively new to me, so will take me some time to get up to speed with them. I stuggled to balance the background ADU between RGB subs - something so simple, yet so hard when you're unfamiliar with the tools. So ended up using pixel math... I'm also still at a loss as the neatimage plug-in doesn't work with PS along with a few other tools like Registar. Yes, I know, I shouldn't have installed Vista64, but I wasn't willing waste the 8gb ram I've installed in the system. CCDStack sure is a pleasure to use, as is PS being 64-bit. Anyway digress, Synthetic lum and 24" lum created and passed through 30 iterations of positive constraint deconvolution to tight things up a little. RGB created and pushed out as an unscaled tiff along with the two lum images before being imported into PS. Levels, curves, the usual drill. I layered the two lums first to blend them in seamlessly - subtle brightness/contrast used to achieve the task, then flattened. Introduced this layer to the RGB and stretched. Created super RGB through flattening and stretch yet again. HPF over entire image, then used colour range tool to select highlights before deleting them to return stars to a natural form. Minor saturation boost to bring out the vibrant hydrogen alpha reds and star colours. As I don't have a noise plug-in I used a Gaussian blur applied via an inverted mask to control the results. Not one of my best, but pleasing none the less. I good test for my new processing system anyway.
Thanks for looking. Hope you like it.
