M25

With a magntude of about 4.5, M25 is a conspicuous cluster in Sagittarius. The number of stars contained by the cluster is not well known and estimates range from about 90 to about 600. Two of the member stars are type M giants and at least one is a Cepheid variable, which can be used to calculate the distance: between 2,000 and 2,300 light-years. M25 is not a very young cluster, at an age of about 90 million years. It spans about 19 light-years.

Image taken September 28, 2009, with the ST-8 camera and the 300 Nikkor lens. Exposure is 2 minutes.