IC 5146 (also Caldwell 19, Sh 2-125, and the Cocoon Nebula) is a reflection/emission nebula and Caldwell object in the constellation Cygnus. The NGC description refers to IC 5146 as a cluster of 9.5 mag stars involved in a bright and dark nebula. The cluster is also known as Collinder 470. It shines at magnitude +10.0/+9.3/+7.2. Its celestial coordinates are RA 21h 53.5m , Dec +47° 16′. It is located near the naked-eye star Pi Cygni, the open cluster NGC 7209 in Lacerta, and the bright open cluster M39. The cluster is about 4,000 ly away, and the central star that lights it formed about 100,000 years ago;the nebula is about 12 arcmins across, which is equivalent to a span of 15 light years.
When viewing IC 5146, dark nebula Barnard 168 (B168) is an inseparable part of the experience, forming a dark lane that surrounds the cluster and projects westward forming the appearance of a trail behind the Cocoon.
Image:
Equipment:
- Astro-Modded Nikon D90
- Sigma 500mm F4 lens
- Sky-Watcher Star Adventurer
- Sky-Watcher Tripod
- Bahintov Mask
- Intervalometer
Acquisition:
- ISO 800, 500mm, F4.0
- 177 x 1′ Lights (Only stacked best 85%, so around 2.5 hours integration time)
- 50 flats
- 200 bias
- 20 darks
Processing:
- Stacked in Pixinsight
- Color calibrated
- Split into LRGB
- DBE, deconvolution, John Rista Noise reduction on all LRGB layers
- RGB combination
- Slight Curves transformation
- Added L data
- Starnet, created image with just stars
- ArcsinH stretch on starless image
- recombined
- DarkStructuresEnhanace
- A bit more curves transformation to taste
Annotated image:
