| CGRO | Compton Gamma Ray Observatory | In English | |
| CTIO | Cerro Tololo Inter-American Observatory (www.ctio.noao.edu) | In English | |
| ESO | European Southern Observatory | In English | |
| GRO | Gamma Ray Observatory | In English | |
| HEAO | High-Energy Astronomy Observatory | In English | |
| HEAO | High Energy Astronomical Observatory | In English | |
| HRSO | High-Resolution Solar Observatory | In English | |
| IORP | Imperial Observatório do Rio de Janeiro | In Portuguese | → Serial publications, periodicals |
| ISO | Infrared Space Observatory | In English | |
| ISO | Imaging Spectrometic Observatory | In English | → Analytical chemistry |
| KPNO | Kitt Peak National Observatory | In English | |
| LRO | Large Radio Observatory | In English | |
| LSO | Large Solar Observatory | In English | |
| MOSPO | Mobile Satellite Photometric Observatory | In English | → Spaceflight engineering, astronautics |
| NAOJ | National Astronomical Observatory of Japan | In English | |
| NOAO | National Optical Astronomy Observatories | In English | |
| NSO | National Solar Observatory | In English | → Solar system |
| OAC | Observatorio Astronómico de Córdoba (www.oac.uncor.edu) | In Spanish | |
| OAO | Orbital Astronomical Observatory | In English | → Spaceflight engineering, astronautics |
| OCA | Observatoire de la Côte d’Azur | In French | |
| OMP | Observatoire Midi-Pyrénées | In French | → Earth sciences |
| ONA | Observatorio Nacional Argentino | In Spanish | |
| OSO | Orbiting Solar Observatory | In English | → Spaceflight engineering, astronautics |
| SOHO | Solar and Heliospheric Observatory | In English | |
| STEREO | Solar TErrestrial RElations Observatory | In English | |
| STO | Solar Terrestrial Observatory | In English | → Solar system |