Messier 100

Target details

Messier 100 (NGC 4321) is a 'grand design' spiral galaxy – one with clear, well-defined arms – in the southern part of Coma Berenices. It's one of the largest and brightest galaxies in the Virgo Cluster, about 55 million light-years away and 107,000 light-years across, roughly 60% the size of the Milky Way. Two small satellite galaxies, NGC 4323 and NGC 4328, orbit it, and the first is joined to M100 by a bridge of luminous matter. NGC 4322 also appears in this image.

Capture details

Data captured over 6 nights between 19th January & 30th March, 2020.
52x 2 minute exposures with Blue filter (Binned 2x2).
52x 2 minute exposures with Green filter (Binned 2x2).
49x 2 minute exposures with Red filter (Binned 2x2).
335x 3 minute exposures with Luminance filter.

Total Exposure = 21.85 hours.

Equipment details

Skywatcher Quattro 200 CF
NEQ6 Pro
Atik 460EX 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)
Automatic Background Extraction - To remove gradients. (RGB Channels)
Dynamic Background Extraction - To remove gradients. (Lum 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, 100 iterations. (Luminance only)
Multiscale Linear Transform - Noise reduction. (Luminace & RGB separately)
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.
TVGDenoise - To reduce noise, with Rangemask to protect Galaxy.
Histogram Transformation - To clip blacks slightly.
HDR Multiscale Transform - To recover detail in the galaxy core & inner arms, with star mask in place.
UnsharpMask - To sharpen with inverted nebula mask in place to exclude stars & background.
Local Histogram Equalisation - To sharpen / add contrast, with previous mask in place.
Dynamic Crop - To crop away most of the background.
Curves Transformation - To desaturate background, with rangemask to protect galaxy & stars.
Curves Transformation - To boost galaxy saturation, with inverted nebula mask in place.
Curves Transformation - To boost contrast, with nebula mask in place.
TVGDenoise - To reduce Deconvolution artifacts on galaxy edge, with range mask in place.

Export as JPEG and import into Lightroom.

Increase Contrast (+15)
Reduce Shadows (-25)
Reduce Blacks (-15)
Boost Saturation (+25)
Boost Magenta Saturation (+50)

Export final JPEG for upload.