Messier 39 is a very loose naked eye open cluster of at least 30 young stars, located in a dense portion of the Milky Way in Cygnus. The cluster is positioned in a beautiful rich region of the sky, with many other open clusters, thousands of stars, regions of dark nebulae, wispy emission and reflection nebulae visible nearby. Of all of the open clusters in Cygnus, M39 is one of the brightest. With an apparent mag. of +5.5, it’s faintly visible to the naked eye and an easy binocular object. M39 is also one of the constellation’s largest clusters and is spread over an apparent diameter of 31 arc minutes, which corresponds to about the same size as that of the full Moon. The cluster is only 800 light-years from Earth and is estimated to be 250 million years old.
Telescope: 16″ f3.75 Dream Scope
Camera: FLI ML16803
Mount: ASA DDM85
Exposure: 2.2 hours (14x300s L + 3x4x300s RGB)
Date: August 2020
Location: Southern Alps, France