M39, An Open Cluster in Cygnus
Messier 39 (NGC 7092) is a large, but very loose open cluster, situated some 9 degrees east and a bit
north of Deneb, the brightest star in the constellation Cygnus. Its distance is only about 800 light years,
and it is thought to be between 230 and 300 million years away. The cluster contains about 30 stars in a
volume of about 7 light years in diameter. M39 is best observed with low power binoculars due to its
angular size of 32 arc minutes, more than the Moon. Under good conditions (i.e, really dark, clear skies), it
can be seen with the unaided eye. Note that the star spikes were added in processing. Normally these are
an artifact of a non-refractor type of telescope (I use a refractor), but it makes the stars of the cluster
standout so I added them.
north of Deneb, the brightest star in the constellation Cygnus. Its distance is only about 800 light years,
and it is thought to be between 230 and 300 million years away. The cluster contains about 30 stars in a
volume of about 7 light years in diameter. M39 is best observed with low power binoculars due to its
angular size of 32 arc minutes, more than the Moon. Under good conditions (i.e, really dark, clear skies), it
can be seen with the unaided eye. Note that the star spikes were added in processing. Normally these are
an artifact of a non-refractor type of telescope (I use a refractor), but it makes the stars of the cluster
standout so I added them.
