The Messier Ten Minute Challenge
M6 - Open Cluster in Scopius
The open cluster M6 (NGC 6405) is also known as the Butterfly Cluster.
At a distance of about 1,600 light-years the diameter of the cluster
is 12 light-years. The age of the cluster is said to be between 95 and
100 million years.
http://www.martin-nicholson.info/tenminutechallenge/m6.htm
Martin Nicholson, Daventry, England.