Bautz–Morgan classification

The Bautz–Morgan classification was developed in 1970 by Laura P. Bautz and William Wilson Morgan to categorize galaxy clusters based on their morphology. It defines three main types: I, II, and III. Intermediate types (I-II, II-III) are also allowed. A type IV was initially proposed, but later redacted before the final paper was published.

Classification

 * A type I cluster is dominated by a bright, large, supermassive cD galaxy; for example Abell 2029 and Abell 2199.
 * A type II cluster contains elliptical galaxies whose brightness relative to the cluster is intermediate to that of type I and type III. The Coma Cluster is an example of a type II.
 * A type III cluster has no remarkable members, such as the Virgo Cluster. Type III has two subdivisions, type IIIE and type IIIS
 * Type IIIE clusters do not contain many giant spirals
 * Type IIIS clusters contain many giant spirals
 * The deprecated type IV was for clusters whose brightest members were predominantly spirals.