NGC 6811 is a large open cluster
located in the constellation of Cygnus. It lies 29-39 thousand light
years away and has a diameter of 14-20 light years. Its angular
size is 15 arcminutes. This is approximately one-half the size of
the full moon. It is sometimes referred to as the Hole in the Cluster
due to the apparent absence of stars at its center.
Most of the stars in the cluster
are 700,000 to one billion years old. The Kepler space mission detected
two planets surrounding stars in this cluster.
NGC 6811 was first observed by John
Herschel in 1829 and added to the General Catalogue of Nebulae and
Galaxies in 1864.