Owl Cluster (Caldwell 13)

[Christopher K.]

Also known as NGC 457, this is a magnitude 6.4 open cluster in Cassiopeia. It lies 2˚06' south-southwest of the A-class magnitude 2.6 star Ruchbah.

Of particular note is the F-class magnitude 4.9 star Phi Cassiopeiae. At the time of the Celestial Handbook's heyday (mid-1970s) there was talk that if the star was a member of the Owl Cluster it would be at a distance of 9300 light-years and thus be one of the most luminous stars known. We know now that Phi Cassiopeiae is about 2300 light-years distant.

The Owl Cluster is part of Stephen James O'Meara's so-called "Ghost Hunt"--a collection of over 100 celestial objects suitable for Halloween viewing. That's tonight! The cluster is currently about fifty-six degrees up.

More information:
Celestial Handbook by Robert Burnham, pp. 530-531.
http://spider.seds.org/ngc/ngc.cgi?457