The "Observatoire des Sciences de l'Univers de l'Université Paris-Sud" (Observatory of the Sciences of the Universe of Université Paris-Sud) has been created in 2001. It has become the Observatoire des Sciences de l'Univers de l'Université Paris-Saclay in 2020, and is currently constituted by three laboratories: AIM, GEOPS and IAS.
OSUs ("Observatoires des Sciences de l'Univers") are created by a decree originating from the two relevant government departments (Research, Public Education) on the basis of a proposition of the Council of the Institut National des Sciences de l'Univers, a department of the CNRS (the main French state research organisation). They have a mandate for contributing to the advances of knowledge in the field of the "Sciences of the Universe" by acquiring observational data, developing, implementing and exploiting relevant observation equipment, and elaborating relevant theoretical and modelling tools. They are also expected to perform the following tasks: providing services linked to their research activities, educating students and research personnel, outreach activities towards the general public (linked with education activities). Staff from a nationally managed set of positions (CNAP: "Astronomers" and "Physical Research Personnel") can be appointed to an OSU. These positions are equivalent to Professors and Assistant Professors with specific tasks linked to observations.
The activities of OSUPS are structured in terms of "national observation services" labelled by INSU. OSUPS hosts a national facility labelled by CNES (the French space agency) and INSU, the IAS calibration facility (station d'étalonnage) dedicated to qualifying and calibrating space instrumentation. It also hosts a centre dedicated to space operations and space data, IDOC (Integrated Data and Operation Center), with attributions defined by national agencies (CNES, INSU) and international agencies (ESA, NASA).