Open star clusters are widely distributed in our galaxy and represent a loose collection of stars which number from a few dozen to a few hundred stars and are weakly-held gravitationally. Perhaps the three most famous such open clusters are the Pleiades (M45) in Taurus, the Beehive (M44) in Cancer and the double cluster in Perseus. They are all characterized with a handful of hot and white prominent stars and nebular material surrounding these stars.

Note: The open cluster NGC 1528 in Perseus illustrated below is within a degree of another bright and large open cluster (NGC 1545, mag 6.2) to the southeast as well as the emission nebula Sh2-209 due west. NGC 1528 can be found to the immediate east of λ-Persei (mag 4.26). Lying at a distance of 1530 light-years away, NGC 1528 is estimated to be between 270 and 370 million years old (depending on the source). Comprised of approximately 100 member stars spanning approximately 16 arc-minutes in diameter and measuring at least 8.78 magnitude, this cluster is well detached from the background sky owing to the fair number of bright member stars in the central core. NGC 1528 is best observed during fall and winter when it is furthest north of the celestial pole after the end of astronomical twilight.

Note: The image below was taken under very poor seeing and will be revisited at the first available opportunity in the fall of 2011.