Crescent Nebula

Target details

The Crescent Nebula sits in Cygnus, about 5,000 light-years away. It's powered by WR 136 (HD 192163), a Wolf-Rayet star – a massive star late in its life. Between 250,000 and 400,000 years ago, when it was a red giant, it shed a slow wind of gas. Now its much faster stellar wind is slamming into that older material, creating a shell and two shock waves, one moving outwards and one moving inwards. The inward shock heats the gas so much that it gives off X-rays.

Capture details

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.

Equipment details

Skywatcher Quattro 200 CF
NEQ6 Pro
Canon 40d (IR Filter removed)
Skywatcher ST-80
QHY5L-II

Processing details

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.