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Contains:  NGC 4559
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NGC 4559 / Caldwell 36 / Koi Fish Galaxy, 


            Chris Sullivan
NGC 4559 / Caldwell 36 / Koi Fish Galaxy

NGC 4559 / Caldwell 36 / Koi Fish Galaxy

Technical card

Resolution: 4859x3193

Dates:Feb. 17, 2019March 5, 2019March 7, 2019March 12, 2019March 13, 2019March 17, 2019March 20, 2019March 25, 2019March 27, 2019March 28, 2019April 2, 2019

Optolong Blue 1.25": 128x120" (gain: 10.00)
Optolong Green 1.25": 82x120" (gain: 10.00)
Optolong H-alpha 7nm 1.25": 25x240" (gain: 10.00)
Chroma Lo-Glow LP filter: 88x120" (gain: 10.00)
Optolong Lum 1.25": 169x120" (gain: 10.00)
Optolong Red 1.25": 222x120" (gain: 10.00)
Optolong Red 1.25": 78x150" (gain: 10.00)

Integration: 27.9 hours

Avg. Moon age: 15.33 days

Avg. Moon phase: 48.56%

Bortle Dark-Sky Scale: 7.50 job: 2623593

RA center: 188.991 degrees

DEC center: 27.959 degrees

Pixel scale: 0.427 arcsec/pixel

Orientation: 270.507 degrees

Field radius: 0.345 degrees

Locations: Home Roof (Bortle 7-8 / Est. Sky Quality: 18.53), Springfield, PA, United States

Data source: Backyard


I've heard this is one of the brighter and easier galaxies on the Caldwell list, but I found it really difficult to 'extract' the dimmer parts of the galaxy from the background - the data are there, but just barely. It's just really tough to do galaxies from my location. On the other hand: For the first time since NGC 7331 (over a year ago), the colors came together without any struggle whatsoever. I'm also really impressed with how well the hydrogen areas pop considering I only gave it a little over an hour.

As for why so many red / a good deal of blue / not so many green: I had a light leak issue when I began this galaxy and reshot my red subs, but Kappa-Sigma clipping actually took care of the light leak issue. I didn't realize that until later, so I included everything anyway. I don't regret it though, because I shot nearly all my reds under a full moon. I also removed the Orion SkyGlow AP filter towards the end of the acquisition here and felt it necessary to reshoot the blue, but it didn't really affect my green at all.



Chris Sullivan
License: None (All rights reserved)

Sky plot

Sky plot


NGC 4559 / Caldwell 36 / Koi Fish Galaxy, 


            Chris Sullivan