| Gumma Astronomical observatory | Japón | Takayama Onsen Fureai Plaza | — |
 Gunma Astronomical Observatory | Japón | Takayama (Gunma) | — |
 Gurley Observatory | Estados Unidos | Marietta | — |
 GUSTO | — | — | — |
| Gwen Observatory | Italia | San Francesco al Campo | — |
| Gyodongdo Manhyangdae | Corea del Sur | — | — |
 Göttingen Observatory | Alemania | Gotinga | — |
| Haagaar Observatory | Noruega | Eina | — |
| Hablainville observatory | Francia | Hablainville | — |
| Hagen Observatory | Alemania | Finnentrop | — |
| Hagerstown observatory | Estados Unidos | Hagerstown | — |
 Haggart Observatory | Estados Unidos | Oregón | — |
| Hainan Island station | República Popular China | Xuanwu | — |
 Hakin Observatory | Reino Unido | Milford Haven | 49,4 m |
| Hakos Observatory | Namibia | Khomas Region | 1.852 m |
 Haldde observatory | Noruega | Alta | — |
| Hale Observatories | — | — | — |
 Hale Solar Laboratory | Estados Unidos | California | — |
| Haleakala-LCO Clamshell #3 | Estados Unidos | Kula | — |
| Haleakala-LCO OGG B #2 | Estados Unidos | Kula | — |
| Hallet Cove observatory | Australia | Hallett Cove | — |
 Halley observatory | Países Bajos | Bernheze | — |
| Halstead Observatory | Estados Unidos | Princeton | — |
 Hamamatsu City Observatory | Japón | Minami-ku | — |
| Hamamatsu-Yuto observatory | Japón | Hamamatsu | — |
| Hamburg observatory (before 1909) | Alemania | Hamburgo | — |
| Hamburg-Georgswerder observatory | Alemania | Hamburgo | — |
| Hamburg-Himmelsmoor observatory | Alemania | Hamburgo | — |
| Hamilton Astronomical Observatory | Nueva Zelanda | — | 40 m |
 Hamilton Astronomical Society Observatory | Nueva Zelanda | — | 40 m |
 Hampstead Observatory | Reino Unido | Hampstead | — |
| Hanau Observatory | Alemania | Hanau | — |
| Hanggao Observatory | — | — | — |
 Hanging Rock Raptor Observatory | Estados Unidos | Condado de Monroe | — |
 Hankasalmi Observatory | Finlandia | Hankasalmi | — |
| Hans-Haffner-Sternwarte | Alemania | Hettstadt | — |
 Hans-Ludwig-Neumann-Sternwarte | Alemania | Distrito del Alto Taunus | — |
 Hans-Nüchter-Sternwarte | Alemania | Fulda | — |
| HAO observatory | Marruecos | Oukaïmeden | — |
| Happy Valley observatory | Nueva Zelanda | Wellington | — |
| Hard Labor Creek Observatory | Estados Unidos | Georgia | — |
 Harestua Solar Observatory | Noruega | Lunner | — |
| Harken Astronomical Observatory | Estados Unidos | Pewaukee | — |
| Harlingten Research observatory | Estados Unidos | Ánimas | — |
| Harlingten Telescope, Greenhill Observatory | Australia | Melton Mowbray | — |
 Harquahala Peak Observatory | Estados Unidos | condado de La Paz | — |
| Harrow observatory | Reino Unido | Municipio de Harrow | — |
| Hartebeesthoek Magnetic Observatory | Sudáfrica | — | — |