The Shapley Sawyer System of Classifying Globular Clusters

The currently accepted system of classifying globular clusters is the Shapley-Sawyer system.

While it leaves a lot to be desired and isn’t as descriptive as the Trumpler system for open clusters, it is useful.

It is simply based on the density of the cluster. A Class I is very dense while a Class XII is very loose.

I have selected examples of each class and made an example of each using the Slooh

telescopes and CCD cameras. All of the pictures are mine

Class I Messier 75(Cliff Hedgepeth)

ClassII Messier 80 (Cliff Hedgepeth)

Class III NGC 6541(Cliff Hedgepeth)

Class IV NGC 5634(Cliff Hedgepeth)

Class V Messier 13(Cliff Hedgepeth)

Class VI Messier 3(Cliff Hedgepeth)

Class VII Messier 22(Cliff Hedgepeth)

Class VIII Messier 14(Cliff Hedgepeth)

Class IX Messier 12(Cliff Hedgepeth)

Class X Messier 68(Cliff Hedgepeth)

Class XI Messier 55(Cliff Hedgepeth)

Class XII NGC 4372(Cliff Hedgepeth)