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.