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Contains:  NGC 5195, Whirlpool galaxy, M 51, NGC 5194
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M51 (Whirlpool Galaxy), 


            Joel Shepherd
M51 (Whirlpool Galaxy)

M51 (Whirlpool Galaxy)

Technical card

Resolution: 1280x997

Dates:March 9, 2018March 11, 2018

Baader Planetarium B 1.25": 22x180" bin 1x1
Baader Planetarium G 1.25": 22x180" bin 1x1
Baader Planetarium L 1.25": 30x180" bin 1x1
Baader Planetarium R 1.25": 22x180" bin 1x1

Integration: 4.8 hours

Avg. Moon age: 23.04 days

Avg. Moon phase: 40.70%

Bortle Dark-Sky Scale: 6.00 job: 1989173

RA center: 202.451 degrees

DEC center: 47.212 degrees

Pixel scale: 1.769 arcsec/pixel

Orientation: 53.581 degrees

Field radius: 0.399 degrees

Locations: Home, Seattle, WA, United States

Data source: Backyard


Subject: M51 (Whirlpool Galaxy): Composed of a dwarf galaxy, NGC-5195, on the left, and its gravitationally interacting galaxy NGC-5194: a grand-design spiral galaxy in Canes Venatici. Roughly 23-25 million light-years distant, NGC-5194 is about a third the size of our Milky Way.

Capture notes: Taken on dark nights, the main notable thing about this image was that it was my first attempt to fully automate my capture process. At the moment I'm using APT (Astro Photography Tool) and if they deliver meridian flip support in the next few months I'll probably stick with it. Auto-focusing has been a challenge -- not that you can tell, but my red channel was a little out of focus for this capture -- but I'm sure with a little patience it'll get better. In any event, I was very excited to get a good night's sleep the night I captured the RGB, and to wake up and find the mount had neatly parked itself at the end.

Processing notes: My L flats were off somehow, so I used PixInsight's DBE to do an additional flat-like correction. Otherwise, this used a pretty ordinary LRGB workflow, with color calibrated vias PhotometricColorCalibration, and with a bit of saturation added by one application of curves.



Joel Shepherd
License: Attribution Creative Commons

Sky plot

Sky plot


M51 (Whirlpool Galaxy), 


            Joel Shepherd