| Brisbane Observatory | Reino Unido | North Ayrshire | — |
| BRITE-Austria | — | — | — |
 BRITE-Heweliusz | — | — | — |
 BRITE-Lem | Polonia | — | — |
| BRITE-Montréal | — | — | — |
| BRITE-Toronto | — | — | — |
| Brixiis Astronomical Observatory | Bélgica | Kruibeke | — |
 Brno Observatory and Planetarium | República Checa | Brno-střed | 305 m |
| Brooklyn Park observatory | Australia | Brooklyn Park | — |
| Brooks Astronomical Observatory | Estados Unidos | Míchigan | — |
| Brooks Observatory | Estados Unidos | Ohio | — |
| Broome Bird Observatory | Australia | Western Australia | — |
| Brorfelde Magnetic Observatory | Dinamarca | Holbæk | — |
| Brownstown Observatory | Irlanda | Condado de Meath | — |
 BRRISON | Estados Unidos | — | — |
| Brukkaros Solar Observatory | Namibia | — | — |
| Bruno Zugna Observatory | Italia | Trieste | — |
 Bruno-H.-Bürgel-Sternwarte | Alemania | Berlín | 83 m |
| Brusque observatory | Brasil | — | — |
| Brynllefrith Observatory | Gales | Pontypridd | — |
| BSA observatory | Italia | Aeropuerto Internacional de Cuneo | — |
| BSCR Observatory | Italia | Santa Maria a Monte | — |
| BSH Byulsem Observatory | Corea del Sur | Busan | — |
| Bucharest Astronomical Observatory | Rumania | Bucarest | 86 m |
| Bucknell Observatory | Estados Unidos | Pensilvania | — |
| Budkov Magnetic Observatory | República Checa | Budkov | — |
 Buehler Planetarium and Observatory | Estados Unidos | Davie | — |
| Buenaventura Suarez observatory | Argentina | La Punta | — |
 Building 20 | Canadá | La Cité-Limoilou | — |
 Bukit Jugra lighthouse | Malasia | Kuala Langat | — |
 Bukit Melawati | Malasia | Selangor | — |
| Burgsolms Observatory | Alemania | Wetzlar | — |
| Burjassot Observatory | España | Burjasot | — |
| Burke-Gaffney Observatory | Canadá | Halifax | — |
| Burleith Observatory | Estados Unidos | Washington D. C. | — |
| Burlington observatory | Estados Unidos | Nueva Jersey | — |
| Burlington remote site Observatory | Estados Unidos | Nueva Jersey | — |
| Burnt Tree Hill Observatory | Estados Unidos | Bristol | — |
 Burrell Memorial Observatory | Estados Unidos | Ohio | — |
| Burwash observatory | Reino Unido | Burwash | — |
| Busot observatory | España | Alicante | — |
 Bussloo public observatory | Países Bajos | Voorst | — |
 Buthiers Observatory | Francia | Buthiers | 87 m |
| Byrne observatory | Estados Unidos | Río Santa Ynez | — |
| Bükki Star | Hungría | Répáshuta | — |
| C. E. K. Mees Observatory | Estados Unidos | Nueva York | — |
| Ca del Monte observatory | Italia | Pavía | — |
| CACTUS | Estados Unidos | — | 610 m |