NGC 663 is young open cluster in the
Cassiopeia constellation with an estimated age of 20–25 million
years. It has an estimated 400 stars and spans about a quarter
of a degree across the sky. This cluster appears to be located
in front of a molecular cloud, although the two are not
physically associated. This cloud has the effect of blocking
background stars from the visual image of the cluster as it lies
at a distance of 300 parsecs.