| Bangui Magnetic Observatory | República Centroafricana | — | — |
| Banyoles observatory | España | Bañolas | — |
| Bar J Observatory | Estados Unidos | Lake Ashby | — |
| Barao Geraldo observatory | Brasil | Barão Geraldo | — |
 Bardsey Bird and Field Observatory | Reino Unido | Aberdaron | — |
| Bareket observatory | Israel | Modi'in-Maccabim-Re'ut | — |
| Barfold observatory | Australia | Glenhope | — |
| Barlad Observatory | Rumania | Bârlad | — |
 Barnard Observatory | Estados Unidos | Oxford | — |
| Barred Owl Observatory | Canadá | Ottawa Kanata | — |
| Barren Grounds Bird Observatory | Australia | — | — |
| Barrow Magnetic Observatory | Estados Unidos | — | — |
| Barton observatory | Australia | Canberra | — |
| BAS observatory | Italia | Scandicci | — |
 Base Amundsen-Scott | — | Región del Tratado Antártico | 2.835 m |
 Basic Environmental Observatory - Musala | Bulgaria | — | 2.925 m |
 Bassano Bresciano observatory | Italia | Bassano Bresciano | 58 m |
| Bastia observatory | Italia | Ravena | — |
| Bastidan observatory | Francia | La Bastide-des-Jourdans | — |
 Batabat Astrophysical Observatory | Azerbaiyán | Zangezur Mountains | 2.100 m |
| Battle Point Observatory | Estados Unidos | Bainbridge Island | — |
| Baugy observatory | Francia | Baugy | — |
 Bavarian Public Observatory Munich | Alemania | Giesing | 539 m |
| Baxter Garden Observatory | Reino Unido | Salisbury | — |
| Bayerwald observatory | Alemania | Neuhütte | — |
| Bayerwald observatory | Alemania | Spiegelau | — |
 Bayfordbury Observatory | Reino Unido | Bayford | — |
| BDI observatory | Australia | Bangor | — |
| Beaconsfield Observatory | Reino Unido | Penn | — |
| Beato Ermanno Observatory | Italia | Impruneta | — |
| Beersel Hills Observatory | Bélgica | Beersel | — |
| Behagi | — | Guipúzcoa | — |
| Behlen Observatory | Estados Unidos | Nebraska | — |
 Beijing Ancient Observatory | República Popular China | Jianguomen Subdistrict | — |
| Beijing Astronomical Observatory | República Popular China | Pekín | 960 m |
| Beijing Ming Tombs Magnetic Observatory | República Popular China | — | — |
| Beilen observatory | Países Bajos | Beelen | — |
| Beimian Tianwentai observatory | República Popular China | Ngari | — |
| Beine-Nauroy Observatory | Francia | Beine-Nauroy | — |
| Belesta observatory | Francia | Bélesta | — |
| Bellavista observatory | Italia | L'Aquila | — |
| Bellino observatory | Italia | Bellino | — |
 Belogradchik Observatory | Bulgaria | Belogradchik | — |
| Belsk Magnetic Observatory | Polonia | — | — |
| Bendestorf observatory | Alemania | Bendestorf | — |
| Beppe Forti Astronomical Observatory | Italia | San Giovanni Evangelista | — |
 BeppoSAX | — | — | — |
| Bergen-Enkheim Observatory | Alemania | Fráncfort del Meno | — |