NGC 6604 is the designation of a small open star cluster located about 5500 light years distant in the constellation of Serpens. In the picture above, the cluster is visible below and slightly to the right of the image's center. It is embedded in an HII nebula which bears the designation Sharpless 54. Within Sh2-54 there are many protostars and many infrared sources, some of these sources are most probably young high-mass stars. The older stellar population in this region has an average age of 4-5 millions years, and are grouped in the open cluster NGC 6604.

Sh2-54 belongs to an extended region nebulosity that includes also the Eagle Nebula and the Omega Nebula.

NGC 6604 in Serpens, which this image is part of.