The “Backward Bracket” Cluster
Posted by Brian Ventrudo
As you tour the deep sky, sometimes you come across objects hard to sort out from the background stars, objects so loose and indistinct they test the patience and imagination of even skilled stargazers. Duds, in other words. The open star cluster M29 in the constellation Cygnus is just such an object. This unloved cluster is often overlooked for richer sights along the backbone of the Milky Way, but it’s not that hard to pick out of the background sky once you know what to look for, and it’s worth inspecting on a late northern-summer evening.
While it’s bright enough at magnitude 6.6 to pick out with binoculars, M29 must be one of the least impressive objects in Messier’s catalog. Many new stargazers who come across this star cluster don’t know when it’s dead center in the field of view. The cluster is located just 1.7º south of Sadr (gamma Cygni), so it should not be hard to find. But with only six bright stars, the cluster can be mistaken for an accidental clump in the Milky Way.
You can tell if you’re seeing M29 by the arrangement of the six bright stars in two groups of three that look like backward curved brackets facing each other like this… )( A larger scope, say 6-8”, will reveal perhaps two dozen stars, but it’s hard to sort them out from the fairly rich stellar background (see image above).
In a sense, M29 is unjustly maligned. If not for intervening dust along the plane of the Milky Way, the 80 stars in this cluster would shine 15x brighter! This young cluster, just 10 million years old, lies about 4,000 light years from Earth.