This is a globular star cluster, although it's a bit atypical for one. A globular star cluster is a "city" of typically hundreds of thousands of stars. Globular clusters typically house very long-lived stars, and are held together by their mutual gravity. They are relatively rare as far as celestial objects go; currently only 158 are known to exist in our home galaxy, the Milky Way. Litebox 15" F/5 Dobsonian, 13mm LVW eyepiece (147x). Anza-Borrego desert, CA.