Onsala Space Observatory (OSO), the Swedish National Facility for Radio Astronomy, provides scientists with equipment to study the Earth and the rest of the Universe.

The observatory operates two radio telescopes in Onsala, 45 km south of Gothenburg, and takes part in several international projects.

The observatory is hosted by Department of Earth and Space Science at Chalmers University of Technology, and is operated on behalf of the Swedish Research Council.

It is used for observations of millimetre wave emission from molecules in comets, circumstellar envelopes, and the interstellar medium in the Galaxy and in extragalactic objects.

It is also used, as part of the European and worldwide networks, for astronomical Very Long Baseline Interferometry (VLBI) observations of star forming regions, radio stars, and active galactic nuclei, and for geodetic VLBI observations to study e.g. crustal dynamics and polar motion.