| Fuente de los matos observatory | Maliaño | — |
| Gandia observatory | Gandía | — |
| Global Oscillations Network Group | — | — |
| Guadarrama Observatory | Madrid | — |
| Gualba Observatory | Gualba | — |
| Guimar-Tenerife Magnetic Observatory | — | — |
| Guirguillano Observatory | Guirguillano | — |
| Helios Ontigola observatory | Ontígola | — |
| Horus observatory | Cártama | — |
| Huelva Observatory | Huelva | — |
| Hyperion Observatory | Caraquiz | — |
| Iluro observatory | Mataró | — |
| Ingenio observatory | Ingenio | — |
| Instituto Volcanológico de Canarias, S.A. | San Cristóbal de La Laguna | — |
| Irydeo Observatory | Camarma de Esteruelas | — |
 Isaac Newton Group of Telescopes | — | — |
| ITelescope Observatory | Nerpio | — |
| Iturrieta observatory | Iturrieta | — |
| Jaen Observatory | Jaén | — |
| Javalambre observatory | La Higuera | — |
| Joan Roget observatory | Ager | — |
| John Beckman observatory | Retamar y el Toyo | — |
| L'Ampolla observatory | La Ampolla | — |
| La Avejerilla observatory | Las Palmas | — |
| La Axarquia Observatory | Chilches | — |
| La Corte Observatory | La Antigua | — |
| La Fecha Observatory | Arroyo de la Encomienda | — |
| La Mata Observatory | La Mata | — |
| La Palma-NEON Observatory | Río Gallegos | — |
| La Puebla de Vallbona observatory | España | — |
| La Romaneta observatory | — | — |
| La Sagra Observatory | Don Domingo | — |
| La Senda observatory | Cabanillas del Campo | — |
| La Vara observatory | Muñás | — |
| Laietania observatory | Parets del Vallès | — |
| Las Negras observatory | Las Negras | — |
| Las Vaguadas observatory | Las Vaguadas | — |
 Lazkuako behatokia | — | — |
| Les Gavarres Astronomical Observatory | San Martivell | — |
| Les Pedritxes observatory | Matadepera | — |
| Les Planes de Son observatory | Alto Aneu | — |
| Linceo observatory | Santander | — |
| Lledoner observatory | ordalía | — |
| Llica d'Amunt Observatory | Llissá de Munt | — |
| Lo Fossil Observatory | Ager | — |
| Los Altos de Arguineguin Observatory | Mogán | — |
| Los Milanos observatory | Cáceres | — |
| Mackay observatory | San Cristóbal de La Laguna | — |