Under dark skies, the Double Cluster in Perseus is visible to the unaided eye. Each cluster contains over 300 blue-white super-giant stars. The two clusters are about 7,000 light-years away and were probably formed from the same star-forming region. First cataloged by Hipparchus as early as 130 B.C, they are currently cataloged as NGC 884 (on the left) and NGC 869.

48 minutes L and 112 minutes RGB on 2011-11-26 using a QSI 583 camera through an Astro-Physics 155mm refractor at f5.4 from northern New Jersey. North is up. ©2011

An older, film-based image of the double cluster. (Comparison to the above ccd-based image shows that the film was not particularly sensitive to blue light.)

Astro-Physics 155 mm refractor at f7.1. One 30 minute exposure on gas-hypersensitized Kodak Pro PPF 400 color negative film. October 12, 1999 from northeast Pennsylvania. ©1999