Pinwheel Galaxy (M101) LHaRGB - June 2021 (Geof Lewis)

Pinwheel Galaxy (M101) LHaRGB - June 2021

This is a summer look at the Pinwheel Galaxy (M101) in Ursa Major, captured in astro twilight, as there is no astro dark between mid May and late July at my 52N location. The colour data in particular was pretty noisy with a very bright background, which I think has resulted in the very muted colours in the galaxy arms. The Ha data was applied at 40% to the RGB data before layering the L data.

VersD - After several attempts processing the colour data, some of which was very bright due to capturing it in a twilight sky, I decided to discard the worst of the RGB subs and start over with the processing. It meant discarding nearly half the green data and about one third each of red and blue. The resulting HaRGB stack had a much cleaner background and hence was much easier to process. I used the same L stack and processing for luminance as in Vers C

B

Description: Adjusted colour balance towards blue and applied more sharpening

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C

Description: Completely dialed back the stretches on both HaRGB and L stacks

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D

Description: Discarded a lot of the colour data, due to bright sky gradients from capturing in a twilight sky

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E

Description: Curves and levels adjustments to slightly lift the galaxy core

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G

Description: Reduced magenta / increased cyan & blues

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H

Description: Adjusted blues to enhance galaxy arms, additional curves adjustments for contrast, upped luminance to give image more punch, high pass filter for galaxy structure and reset background levels.

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I

Description: Completely reprocessed April 2022 - no colour adjustments other than background neutralisation and set white point for colour balance.

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J

Description: Applied StarX to final image as an experiment

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K

Title: Re-processed by a friend using PI, with BlurX, etc.

Description: I was never happy with this image despite countless attempts to process it, so I gave up. With the recent hype over BlurX and me considering investing in PI, I asked a friend to show me what he could do with it. This is a pretty quick process by him, but still far better than anything I could get over many hours, days and weeks trying....!!

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L

Title: My LRGB attempt at this challenging target using PI

Description: It was my friend's version KK) using PI last year, that was the final lightbulb momemnt for me to trial PI myself, though it's taken me several months to get around to it. Fortunately one of the benefits of being post hip surgery, is the time to play with and learn the new PI tools. Eventually I'll try adding Ha data, but for now here is my LRGB version.

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M

Title: LHaRGB built in PI using PixelMaths

Description: I used Pixel Maths in Pi to try to avoid double counting the red signal captured in both R and Ha data

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N

Title: LHE and HDR

Description: Used LocalHistorgamEqualisation to bring out the vein details in the galaxy arms and improve contrast in the core, with additional application of HDR to further reveal structures in the galaxy core region.

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Status	Advanced success
Started	...
Astrometry.net job	5838087
PixInsight job	JA2I5TGPWQG9TUT3IKXDM6DJZBLBDBP6
PixInsight queue size	n/a
PixInsight stage	TASK_LOG

RA (center)	14h03m10s.406
RA (top/left)	14h02m15s.447
RA (top/right)	14h02m08s.783
RA (bottom/right)	14h04m04s.951
RA (bottom/left)	14h04m12s.786

Dec (center)	+54°20′59″.32
Dec (top/left)	+54°32′47″.56
Dec (top/right)	+54°09′55″.55
Dec (bottom/right)	+54°09′08″.24
Dec (bottom/left)	+54°32′00″.33

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