Messier 81 is a spiral galaxy about 12 million light-years away in the constellation Ursa Major. Due to its proximity to Earth, large size and active galactic nucleus (which harbors a supermassive black hole), Messier 81 has been studied extensively by professional astronomers.
The galaxy's large size and relatively high brightness also make it a popular target for amateur astronomers.
Data captured over 7 nights between 1st January & 26th February, 2019.
78x 2 minute exposures with Blue filter (Binned 2x2).
80x 2 minute exposures with Green filter (Binned 2x2).
88x 2 minute exposures with Red filter (Binned 2x2).
534x 3 minute exposures with Luminance filter.
Total Exposure = 34.9 hours.
Skywatcher Quattro 200 CF
Atik 428EX Mono
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. (Each Channel)
Linear Fit - To match brightness of RGB channels (RGB Channels Separately)
Channel Combination - To combine RGB channels.
Photometric Colour Calibration - To calibrate colours.
SCNR - To remove green cast.
Deconvolution - To bring out some fine detail & tighten stars, 75 iterations. (Luminance only)
Multiscale Linear Transform - Noise reduction. (Luminace only)
Histogram Transformation - To stretch the RGB & Lum. (Using statistics process to keep background levels evenly)
LRGB Combination - To blend my luminance image with my RGB image.
HDR Multiscale Transform - To recover detail in the galaxy core, with star mask in place.
UnsharpMask - To sharpen with mask in place to exclude stars & background.
Curves Transformation - To darken blacks slightly.
Dark Structure Enhance Script - To pull back some contrast in the galactic arms.
Curves Transformation - To desaturate background, with range mask in place.
Curves Transformation - To saturate nebula, with starless range mask in place.
Export as JPEG and import into Lightroom.
Increase Contrast (+15)
Increase Saturation (+25)
Increase Magenta Saturation (+50)
Export final JPEG for upload.