| Fitz-Randolph Observatory | Estados Unidos | Universidad de Princeton | — |
| Five College Radio Astronomy Observatory | Estados Unidos | Massachusetts | 306 m |
| Flamborough Bird Observatory | Reino Unido | — | — |
| Flarestar Observatory | Malta | San Ġwann | 126 m |
| Flint observatory | Estados Unidos | Míchigan | — |
| Flower and Cook Observatory | Estados Unidos | Filadelfia | — |
| FOAH Observatory | Estados Unidos | Magdalena | — |
| Foligno observatory | Italia | — | — |
 Foothill Observatory | Estados Unidos | California | — |
| Forcarei observatory | España | robledal | — |
| Ford Observatory | Estados Unidos | Nueva York | — |
 Former Nižbor observatory | República Checa | Nižbor | — |
 Former observatory of Brussels | Bélgica | Saint-Josse-ten-Noode | — |
| Fort Churchill Magnetic Observatory | Canadá | — | — |
| Fort Pius Observatory | España | El Fort Pienc | — |
| Fosseway Observatoy | Reino Unido | Radstock | — |
| Four Winds Observatory | Estados Unidos | Lake Leelanau | — |
| Fox Park Public Observatory | Estados Unidos | Condado de Eaton | — |
| Foxfire Village observatory | Estados Unidos | Foxfire | — |
| Frances E. Barnard Memorial Observatory | Estados Unidos | California | — |
| Francis Marion University Observatory | Estados Unidos | Carolina del Sur | — |
| Francisquito observatory | Estados Unidos | Santa Clarita | — |
 Frankfurt observatory | Alemania | Fráncfort del Meno | — |
 Franz-Kroller-Sternwarte | Austria | Traiskirchen | — |
 François-Xavier Bagnoud Observatory | Suiza | Saint-Luc | 2.200 m |
| Frasnes-Lez-Anvaing observatory | Bélgica | Frasnes-lez-Anvaing | — |
| Freconrupt observatory | Francia | La Broque | — |
| Fredericksburg Magnetic Observatory | Estados Unidos | — | — |
 Frei Rosário Astronomical Observatory | Brasil | Caeté | 1.751 m |
| Frelinghien military observatory | Francia | Frelinghien | — |
 Fremont Peak Observatory | Estados Unidos | California | — |
| Fresno Magnetic Observatory | Estados Unidos | — | — |
| Frignano observatory | Italia | Frignano | — |
 Fringilla Field Station | Rusia | Zelenogradsky District | — |
 Fritz-Weithas-Sternwarte | Alemania | Neumarkt in der Oberpfalz | 595 m |
| Frog Rock observatory | Australia | Frog Rock | — |
| Frontier Observatory for Research in Geothermal Energy | Estados Unidos | Milford | — |
| FRoST observatory | Estados Unidos | Flagstaff | — |
| Frosty Cold Observatory | Estados Unidos | Addison | — |
| Frosty Drew Observatory | Estados Unidos | Rhode Island | — |
| Fuensanta de Martos | España | Fuensanta de Martos | — |
| Fuente de los matos observatory | España | Maliaño | — |
 Fuertes Observatory | Estados Unidos | Ithaca | 274 m |
| Fujieda observatory | Japón | Fujieda | — |
| Fukuchiyama and Kannabe observatory | Japón | Fukuchiyama | — |
| Fukushima Jōdodaira Astronomical Observatory | Japón | Fukushima | — |
| Furnace Brook Observatory | Estados Unidos | Cranston | — |
| Furstenfeldbruck Magnetic Observatory | Alemania | — | — |