IC5146 known as the Cocoon Nebula taken from Al Sadeem Observatory last October 4-5, 2018 using GSO RC 8 inch telescope and ZWO1600MC-cool CMOS camera mounted on Skywatcher EQ6. 2.5 hour total exposure time guided. Stacked and post-processed in Pixinsight.


The Cocoon Nebula (designated IC5146 and Caldwell 19) is a complex (could be classified as reflection, dark, and emission) nebula situated about 3300-3900 light-years away in the constellation of Cygnus.  It was discovered by British astronomer Thomas E. Espin on August 13, 1899 who described “its long and fairly starless trail is like the proverbial worm who ate its way to the end of the leaf before time for change”. It is an active stellar nursery consisting of a cluster of magnitude +9.5 stars within a surrounding huge cloud of low density gas. It spans about 12 arc-minutes of the sky equivalent to about 15 light-years diameter.

The nebula is being illuminated by the hot, massive B-type star BD +46°3474 which was estimated 14±4 times the mass of the Sun, whose surface temperature of 30,000 to 35,000 degrees, and is about 100,000 years old through ionization of the surrounding gas, mainly of hydrogen and oxygen, producing a reddish/pinkish color. Dark patches seen within the nebula are regions containing denser gas blocking the passage of light from background stars.

With an apparent magnitude of +7.2, its associated cluster of stars can be revealed in mid-sized (6 to 10 inch) telescopes and is found near the star Pi Cygni and the open cluster M39 (see star map below). It will appear as a faint smudge within a background of several stars when observed visually. Long exposure photography is essential to reveal beautiful red cocoon-shaped nebulosity.

Location of Cocoon Nebula (IC5146) in the constellation of Cygnus (Image Credit: IAU, Sky & Telescope)

Gendler, R. (n.d.). The Cocoon Nebula (IC 5146, S125). Retrieved from

Plait, P. (2014, October 27). An Ionized Flower Blooms in Space. Bad Astronomy: The Entire Unierse in Blog Form. Retrieved from

Plotner, T. (2015, December 25). The Cosmic Cocoon: IC 5146 by Tom V. Davis. Universe Today: Space and astronomy news. Retrieved from

Wikipedia contributors. (2018, August 27). IC 5146. In Wikipedia, The Free Encyclopedia. Retrieved from