The Pinwheel Galaxy

Target details

The Pinwheel Galaxy (Messier 101) is a face-on spiral galaxy in Ursa Major, about 21 million light-years away. At 170,000 light-years across it's roughly the same size as the Milky Way. Its disc holds around 100 billion Suns' worth of mass, with a small central bulge of about 3 billion. M101 is known for its many large, bright H II regions – clouds of hydrogen lit up by young stars.

Capture details

Data captured 16th, 20th, 21st, 22nd, 24th & 25th February; 11th March, 2018.
30x 3 minute exposures with Blue filter (Binned 2x2).
30x 3 minute exposures with Green filter (Binned 2x2).
30x 3 minute exposures with Red filter (Binned 2x2).
237x 3 minute exposures with Luminance filter.
54x 10 minute exposures with Ha filter.
Total Exposure = 25.3 hours.

Equipment details

Skywatcher Quattro 200 CF
NEQ6 Pro
Atik 428EX Mono
Skywatcher ST-80
QHY5L-II

Processing details

This image was processed in Pixinsight & Lightroom.
Calibration and Stacking in Pixinsight using Batch PreProcessing
Dynamic Crop - To remove black edges & integration artifacts. (Each Channel)
Dynamic Background Extraction - To remove gradients. (R, G, B, Lum & Ha separately)
Morphological Transformation - Morphological Selection to reduce star sizes for Red & Green channels to get consistant sizes.
Channel Combination - To combine RGB channels.
Photometric Colour Calibration - To calibrate colours.
Deconvolution - To bring out some fine detail & tighten stars, 50 iterations. (Luminance & Ha separately)
Multiscale Linear Transform - Noise reduction. (Each Channel)
Histogram Transformation - To stretch the RGB, Lum & Ha. (Using statistics process to keep background levels evenly)
LRGB Combination - To blend my luminance image with my RGB image.
Channel Extraction - To split RGB.
Pixelmath - To combine 75% of Red with 50% of Ha.
Channel Combination - To merge R, G & B.
Histogram Transformation - To clip blacks.
Curves Transformation - To boost contrast.
UnsharpMask - To sharpen with mask in place to exclude stars & background.
Curves Transformation - To decrease saturation of background, with inverted range mask in place (stretched to clip black and boost mids).
TVGDenoise - To denoise background, with inverted range mask in place.
TVGDenoise - To denoise galaxy, with range mask in place.
TVGDenoise - To further denoise background, with inverted range mask in place.
Histogram Transformation - To clip blacks.
Curves Transformation - Increase Saturation for galaxy with mask in place to protect background and stars.
Curves Transformation - Increase Blue channel slightly for galaxy with mask in place to protect background and stars.
Histogram Transformation - To clip blacks in galaxy with range mask.
Histogram Transformation - To clip blacks in background with inverted range mask.
Star Reduction Script - To reduce stars slightly with sharpen enabled.

Export as JPEG and import into Lightroom.
Contrast Boost (+15)
Clip Blacks (-15)
Increase Blue Saturation (+34)

Export final JPEG for upload.