G
| Name | Established | Location |
| Galaxy Evolution Explorer (GALEX) | 2003 | Caltech, JPL |
| Gauribidanur Radio Observatory | 1976 | Gauribidanur, Karnataka, India |
| Gemini Observatory | 1999 | Southern Operations Center: La Serena, Chile; Northern Operations Center: Hilo, Hawaii, USA |
| Giant Meterwave Radio Telescope (GMRT) | 1995 | Pune, Maharashtra, India |
| Gifford Observatory | 1912 | Wellington, New Zealand |
| Girawali Observatory | 2006 | Pune, Maharashtra, India |
| Glen D. Riley Observatory | 1973 | Naperville, Illinois, USA |
| Godlee Observatory | 1902 | Manchester, England |
| Goodsell Observatory | 1887 | Northfield, Minnesota, USA |
| Goethe Link Observatory | 1939 | Brooklyn, Indiana, USA |
| Goldendale Observatory | 1973 | Goldendale, Washington, USA |
| Gornergrat (HFSJG) (defunct) | 1967–2005 | Gornergrat, Switzerland |
| Granat (defunct) | 1989–1999 | Highly eccentric Earth orbit |
| Gran Telescopio Canarias | 2006 | Canary Islands, Spain |
| Grant O. Gale Observatory | 1984 | Grinnell, Iowa, USA |
| Green Bank Telescope, | Green Bank, West Virginia, USA | |
| Green Point Observatory, | 1961 | Sutherland, New South Wales, Australia |
| Grenfell Observatory | 2012 | Corner Brook, Newfoundland and Labrador, Canada |
| Griffith Observatory | 1935 | Los Angeles, California, USA |
| Guillermo Haro Observatory | 1972 | Cananea, Sonora, Mexico |
Read more about this topic: List Of Astronomical Observatories