Hi Javio:
I'd like to submit the following rendition of the Ghost Nebula, a modified version of an image that I posted to the Gallery in October.
Processing was done entirely with PixInsight, except for use of CCDInspector to evaluate subexposures and to monitor overall specs during processing.
Image capture details
Telescope: PlaneWave CDK17, with a focal reducer at f/4.5.
Mount: Paramount ME.
Camera: SBIG STL-4020M.
Exposures: Total of approximately 15 hours: about 6 hours luminance unbinned, and about 3 hours in each of red, green, and blue with 2x2 binning; 10 minute subexposures in all channels.
Flat field correction: using twilight flats.
Image capture: TheSkyX, MaxIm DL, FocusMax.
Image scales: Unbinned pixel size 0.78", frame about 25' on a side.
Imaged between August 6 and 26 2011 from rural British Columbia, Canada.
PixInsight processsing highlights
LUMINANCE:
Deconvolution (reduced Aspect ratio and nonzero Rotation to correct for guiding problems on gusty nights) ; ATrous (star masked, positive bias on layers 3 and 4 to increase contrast on extended nebula structures); UnsharpMask (applied to brightest core region of nebula); ACDNR (luminance mask).
CHROMINANCE:
RGB BackgroundNeutralization; LRGBCombine (Saturation=0.15); CurvesTransformation (mild additional saturation boost); Histograms (colour balance and black point); MorphologicalTransformation (2-way Morphological Selection to circularize and erode small stars); CurvesTransformation and UnsharpMask combination tailored for bright stars (to reduce halos and sharpen cores, modified from earlier version).
Best wishes to all,
Howard.
