Open Cluster M21 in Sagittarius

This cluster is a fairly compact knot of about six 8th magnitude stars with several dozen added members. The total population is about 57 stars at a distance of around 2200 light years. The diameter of the cluster is about 17 light years.

Note, the nebula M20 is very near to this nebula. You will see that by moving your mouse over this image. If you hold the mouse down, you will also see this nebula in association with the Lagoon nebula and a part of the Saggitarius Milky Way.

Images taken with TEC-140 Telescope mounted on Losmandy G11 mount. Camera used was a Canon EOS20D used at prime focus.

Fifteen 3 minute exposures dark, flat, and bias compensated; aligned and stacked; background removed and Digitaly Developed in ImagesPlus 2.75 beta 1.