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Contains:  Cocoon nebula, IC 5146
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Cocoon Nebula (2019) - HaRGB with RGB Stars, 


            Kurt Zeppetello
Cocoon Nebula (2019) - HaRGB with RGB Stars

Cocoon Nebula (2019) - HaRGB with RGB Stars

Technical card

Resolution: 4578x3402

Dates:Aug. 1, 2019Aug. 4, 2019Aug. 10, 2019Aug. 11, 2019Aug. 19, 2019

ZWO B 1.25" optimized for ASI1600: 78x60" (gain: 139.00) -10C bin 1x1
ZWO G 1.25" optimized for ASI1600: 67x60" (gain: 139.00) -10C bin 1x1
ZWO Ha 7nm 1.25": 140x180" (gain: 139.00) -10C bin 1x1
ZWO L 1.25" optimized for ASI1600: 169x60" (gain: 139.00) -10C bin 1x1
ZWO R 1.25" optimized for ASI1600: 80x60" (gain: 139.00) -10C bin 1x1

Integration: 13.6 hours

Darks: ~12

Flats: ~15

Bias: ~20

Avg. Moon age: 8.77 days

Avg. Moon phase: 53.13%

Bortle Dark-Sky Scale: 5.00

Temperature: 15.00 job: 2891838

RA center: 21h 53' 33"

DEC center: +47° 16' 33"

Pixel scale: 1.204 arcsec/pixel

Orientation: 171.415 degrees

Field radius: 0.954

Locations: Happy Frog Observatory, Monroe, Connecticut, United States

Data source: Backyard


Surprisingly this is my first image of the this colorful emission/reflection nebula. There are certain objects that most astrophotographers do when they are first starting out like the Orion Nebula. The Coccon is not that popular but it is one that people in the Northern Hemisphere usually do with in the first year or so. For a number reasons I am just getting around to it now. I was planning on doing a normal LRGB image but then I saw a fabulous image on Astrobin by Luca Marinelli Link to image ( where he added a whole bunch of Ha data. I decided to give it shot as well. Although I did not capture as much Ha, I did capture enough to see the streamers (jets) that come off the top and bottom of the nebula (it is very faint even with seven hours worth of Ha).

Real Imaging Dates:
Date: 8-1-19, 8-4-19, 8-10-19, 8-11-19, 8-19-19, 8-20-19, 8-23-19
The Cocoon Nebula (IC 5146) is about 15 light-years wide and 3,300 light years away towards constellation of the Swan (Cygnus). The nebula itself is a young star-forming region glowing inside a dim molecular cloud which extends to the left on the image. Massive amounts of excited hydrogen gas account for the reddish glow of this stellar nursery along with many hot young blue stars. The source of the glow is the bright star near the center of the nebula estimated to only a few hundred thousand years old.

I find processing HaRGB images to be the toughest of all, even harder than SHO or HOO for some reason and this was no exception. I was trying to keep a natural look yet show the Ha jets on the top and bottom, however, it seems one sacrifices for the other. Using PixInsight I did a RGB combination, then a LRGB combination, and then combined the Ha into the red channel for the final combination. I tried a last combination of adding the Ha as a luninosity layer but it took away from the natural look that I was after. I also have to give a shout out to Gary Imm for assisting me with combining RGB stars into a narrowband image.



Kurt Zeppetello
License: None (All rights reserved)

Sky plot

Sky plot


Cocoon Nebula (2019) - HaRGB with RGB Stars, 


            Kurt Zeppetello