Messier 39

Main objects: M 39, PGC 86597, PGC 167495, PGC 167481

The Christmas tree of constellation Cygnus

For the small-telescope observers of the summer nights, one of the most beautiful views is the Swan constellation's large open cluster. The Messier 39 is relatively easy to find in the sky as it is only 9 degrees from the Deneb, the brightest star of the constellation - and a member of the Great Summer Triangle. The size of the set is slightly larger than the apparent diameter of the full moon, so it offers a wonderful view with binoculars and smaller magnifications. 

Of course, Messier 39 was first cataloged by Charles Messier in 1764, but this discovery is also related to the French Guillaume Le Gentil, who observed the open cluster in 1749.

The open cluster has 30 stars physically, each of which is a 200-300 million-year-old stars. It is interesting that the members of the cluster are approaching us at a speed of 28 km/s. Despite of the continuously decreasing distance, we are talking about a "close" Messier object, as the Pleiades (M45), M40, Praesepe (M44) and probably M7 closer to us.

The location of the brighter bluish-colored stars is clearly triangular, but I think they can resemble a Christmas tree, so for me this is the Christmas tree of the Cygnus constellation.

There are also two pairs of beautiful, but tiny and faint galaxies on the photo: PGC 86597 and PGC 167495. Unfortunately, we don't have much information about these galaxies.

The photograph was taken in almost undisturbed conditions with an exposure time of nearly two hours using 60 x 120 seconds exposures. After the Messier 92, this was the second shot made with a 200/800 mm reflector which purchased in the summer of 2018.

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