R
| Name | Established | Location |
| Radcliffe Observatory | 1772 | Oxford, England. Moved to Durban, South Africa in 1939 |
| Rainwater Observatory | French Camp, Mississippi, USA | |
| Ralph A. Worley Observatory | 1964 | Shreveport, Louisiana, USA |
| Rankin Science Observatory | 1963 | Appalachian State University, Boone, North Carolina, USA |
| Rattlesnake Mountain Observatory | 1971 | Hanford Reach National Monument, Washington, USA |
| Red Barn Observatory | 2006 | Ty Ty, Georgia, USA |
| Red Buttes Observatory | 1994 | Laramie, Wyoming, USA |
| Riley Observatory | 1974 | Naperville, Illinois, USA |
| RIT Observatory | Rochester, New York, USA | |
| Ritter Observatory | Toledo, Ohio, USA | |
| Robert Brownlee Observatory | Lake Arrowhead, California, USA | |
| Robinson Observatory | Orlando, Florida, USA | |
| Robotic Lunar Observatory | 1995 | Flagstaff, Arizona, USA |
| Rogers Observatory | 1981 | Traverse City, Michigan, USA |
| Rolnick Observatory | Westport, Connecticut, USA | |
| Rome Observatory | Italy | |
| Rothney Astrophysical Observatory | 1984 | Priddis, Alberta, Canada |
| Royal Observatory, Greenwich | 1675 | Greenwich, England |
| Royal Observatory, Edinburgh | 1896 | Edinburgh, Scotland |
| Roque de los Muchachos Observatory | 1979 (officially inaugurated in 1985) | La Palma, Canary Islands, Spain. |
| Rosemary Hill Observatory | Bronson, Florida, USA | |
| Rozhen Observatory | 1981 | Peak Rozhen, Bulgaria. |
| Rutherford Observatory | 1920s | New York City, New York, USA |
| RT-32 | 1960 | Irbene, Latvia. |
Read more about this topic: List Of Astronomical Observatories