NGC 457 - Owl Cluster, ET Cluster

NGC 457 is one of the finer star clusters in Cassiopeia. It was discovered by Friedrich Wilhelm Herschel in 1787. Besides its official name, NGC 457 is also known as the "Owl cluster" or the "ET Cluster". Two bright stars, 5th magnitude φ1 Cas and 7th magnitude φ2 Cas can be imagined as eyes. Scattered rows of faint stars make up the arms, and the rest of the cluster forms a body.

NGC 457 contains over one hundred stars. It is bright, large, quite rich, and somewhat triangular-shaped with three streams of stars protruding NNW, SW, and eastward from a moderately compressed center. It has at least fifty 8.5 to 12th magnitude stars, and thirty 13th to 14th magnitude stars sprinkled within its boundaries. A gathering of bright stars is south, and a dark patch north, of the cluster center. A red star lies at the northern edge. The beautiful yellow and blue double Phi Cassiopeiae is on the SE edge.

NGC 457 is a young star cluster about 9,700 light years away. The bright star φ1 Cas is on the SE end of the group, but its membership is unlikely. If it is a true member, this star would have a luminosity of 275,000 suns.