| Challenge List of Globular Clusters | |
| C 1. | G1 in M-31 (Mayall-II) |
| C 2. | Any other Gn in M-31 |
| C 3. | C39 or U49 in M-33 |
| C 4. | Any of the Palomar globular clusters, except Palomar |
| C 5. | Any non-Messier, non-NGC, non-IC globular cluster |
| C 6. | NGC 5053 |
| C 7. | NGC 5466 |
| C 8. | NGC 4147 |