| Gevelsberg observatory | Alemania | Breckerfeld | — |
| Geyserland Observatory | Nueva Zelanda | Rotorua Lakes District | — |
| Ghana Satellite Earth Station | Ghana | Ga Oeste | — |
| Ghezz observatory | Suiza | Acquarossa | — |
| GiaGa Observatory | Italia | Pogliano Milanese | — |
| Gibraltar Point Bird Observatory | Reino Unido | — | — |
| Gieres observatory | Francia | akja | — |
 Gifford Observatory | Nueva Zelanda | Región de Wellington | — |
 Gifu Astronomical Observatory | Japón | Gifu | — |
| Gimhae observatory | Corea del Sur | Gimhae | — |
| Gingin Magnetic Observatory | Australia | Western Australia | — |
| GINOP-KHK observatory | Hungría | Mátraszentimre | — |
| Giordano Bruno National Astronomical Observatory and Planetarium | Bulgaria | Dimitrovgrad | — |
| Giordano Bruno Observatory | Italia | Brallo di Pregola | — |
 Girawali Observatory | India | — | — |
| Gissar Observatory | Tayikistán | Hisor | 743 m |
| Giuseppe Conzo's Observatory | Italia | — | — |
| Giuseppe Piazzi observatory | Italia | Ponte in Valtellina | — |
 Givatayim Observatory | Israel | Distrito de Tel Aviv | — |
| Glasgow observatory | Reino Unido | Ciudad de Glasgow | — |
 Glashütte Observatory | Alemania | Glashütte | — |
 Glen D. Riley Observatory | Estados Unidos | Illinois | — |
| Glenlea Astronomical Observatory | Canadá | Winnipeg | — |
| Glenlea Magnetic Observatory | Canadá | — | — |
| Glenlee Observatory | Australia | Glenlee | — |
| Glentower, Auchintore Road, Fort William | Reino Unido | Highland | — |
| Global Oscillations Network Group | España | — | — |
| Glyn Marsh Observatory | Reino Unido | Isla de Man | — |
| Gnangara Magnetic Observatory | Australia | Western Australia | — |
| Gnevsdorf observatory | Alemania | Buchberg | — |
 GNS Science | Nueva Zelanda | — | — |
| Go-Chome and Kobe-Suma observatory | Japón | Kobe Bryant | — |
| Goat Mountain Astronomical Research Station | Estados Unidos | Homestead | — |
| Godalming observatory | Reino Unido | Godalming | — |
 Godlee Observatory | Reino Unido | Mánchester | — |
 Golden Ears Observatory | Canadá | Maple Ridge | 41 m |
| Golden Hill Observatory | Reino Unido | Sturminster Newton | — |
 Goldendale Observatory State Park | Estados Unidos | Washington | — |
| Goma Volcanological Observatory | República Democrática del Congo | Goma | — |
 Goodsell Observatory | Estados Unidos | Northfield | — |
| Gor City Observatory | — | — | — |
| Gorgonzola Observatory | Italia | Gorgonzola | — |
 Gornergrat Kulm Hotel | Suiza | Zermatt | — |
| Gothers Observatory | Reino Unido | St Austell | — |
| GOTO-N | — | — | — |
| GOTO-S | Australia | New South Wales | — |
| Gottolengo observatory | Italia | Gottolengo | — |
| Governor Aker Observatory | Estados Unidos | Safford | — |