The Crescent Nebula is an emission nebula in the constellation Cygnus, about 5000 light-years away from Earth. It is formed by the fast stellar wind from the Wolf-Rayet star WR 136 (HD 192163) colliding with and energizing the slower moving wind ejected by the star when it became a red giant around 250,000 to 400,000 years ago. The result of the collision is a shell and two shock waves, one moving outward and one moving inward. The inward moving shock wave heats the stellar wind to X-ray-emitting temperatures.
Data captured 12th August, 2017.
16x 15 minute exposures at ISO400.
This was the first session where I used 15 minute exposures, out of 19 images only 4 were deemed not to be a high enough quality. Interestingly the FWHM figures for this exposure length were no larger than previous 10 minute exposures meaning I could in theory go for even longer exposures.
This will not be the final image, I plan to shoot this target with a hydrogen-alpha filter so the final image will be monochrome.
Skywatcher Quattro 200 CF
Canon 40d (IR Filter removed)
This image was processed in Pixinsight & Lightroom.
Calibration and Registration using Batch PreProcessing script, using the Superpixel for the debayer method.
Dynamic Crop - Cropped to remove any black edges.
Dynamic Background Extraction - Applied to remove background gradients.
Deconvolution - To bring out some fine detail. (Not very effective in this image due to lack of good data)
Multiscale Linear Transform - Noise reduction.
Histrogram Transformation - To stretch the image and bring out the data.
Curves Transformation - To increase contrast.
Export as JPEG and import into Lightroom.
Darken blacks slightly (-25)
Increase contrast (+25)
Export final JPEG for upload.