The Palomar globular clusters were discovered in the 1950s on the survey plates of the first Palomar Observatory Sky Survey (POSS). The list of astronomers who first identified the objects as globular clusters includes some famous names, among them Edwin Hubble, Walter Baade, Fritz Zwicky, Halton Arp and George Abell. Several of the Palomar globulars--including Palomar 6, Palomar 7, Palomar 9, Palomar 10 and Palomar 11--are nearby clusters of average size that just happen to be heavily obscured by dust in our line of sight.

 

Others--including Palomar 3, Palomar 4, and Palomar 14 --are giant globulars that are very far away in the extreme outer halo of the Milky Way. Although the objects vary greatly in degree of difficulty--from easy to nearly impossible--observing the whole list is a very challenging observing project for owners of big telescopes.