Gaia (spacecraft) in the context of Hipparcos

A star catalogue is an astronomical catalogue that lists stars. In astronomy, many stars are referred to simply by catalogue numbers. There are a great many different star catalogues which have been produced for different purposes over the years, and this article covers only some of the more frequently quoted ones. Star catalogues were compiled by many different ancient people, including the Babylonians, Greeks, Chinese, Persians, and Arabs. They were sometimes accompanied by a star chart for illustration. Most modern catalogues are available in electronic format and can be freely downloaded from space agencies' data centres. The largest is being compiled from the spacecraft Gaia and thus far has over a billion stars.

Completeness and accuracy are described by the faintest limiting magnitude V (largest number) and the accuracy of the positions.

The Space Telescope Science Institute (STScI) is the science operations center for the Hubble Space Telescope (HST), science operations and mission operations center for the James Webb Space Telescope (JWST), and science operations center for the Nancy Grace Roman Space Telescope. STScI was established in 1981 as a community-based science center that is operated for NASA by the Association of Universities for Research in Astronomy (AURA). STScI's offices are located on the Johns Hopkins University Homewood Campus and in the Rotunda building in Baltimore, Maryland.

In addition to performing continuing science operations of HST and preparing for scientific exploration with JWST and Roman, STScI manages and operates the Mikulski Archive for Space Telescopes (MAST), which holds data from numerous active and legacy missions, including HST, JWST, Kepler, TESS, Gaia, and Pan-STARRS.

The European Space Operations Centre (ESOC) serves as the main mission control centre for the European Space Agency (ESA) and is located in Darmstadt, Germany. ESOC's primary function is the operation of uncrewed spacecraft on behalf of ESA and the launch and early orbit phases (LEOP) of ESA and third-party missions. The Centre is also responsible for a range of operations-related activities within ESA and in cooperation with ESA's industry and international partners, including ground systems engineering, software development, flight dynamics and navigation, development of mission control tools and techniques and space debris studies.

ESOC's current major activities comprise operating planetary and solar missions, such as Mars Express and the Trace Gas Orbiter, astronomy & fundamental physics missions, such as Gaia and XMM Newton, and Earth observation missions such as CryoSat2 and Swarm.

Hipparcos was a scientific satellite of the European Space Agency (ESA), launched in 1989 and operated until 1993. It was the first space experiment devoted to precision astrometry, the accurate measurement of the positions and distances of celestial objects on the sky. This was the first practical attempt at all-sky absolute parallax measurement, something not possible with groundside observatories, and thus represented a fundamental breakthrough in astronomy. The resulting high-precision measurements of the absolute positions, proper motions, and parallaxes of stars enabled better calculations of their distance and tangential velocity; when combined with radial velocity measurements from spectroscopy, astrophysicists were able to finally measure all six quantities needed to determine the motion of stars. The resulting Hipparcos Catalogue, a high-precision catalogue of more than 118,200 stars, was published in 1997. The lower-precision Tycho Catalogue of more than a million stars was published at the same time, while the enhanced Tycho-2 Catalogue of 2.5 million stars was published in 2000. Hipparcos's follow-up mission, Gaia, was launched in 2013.

The word "Hipparcos" is an acronym for High Precision Parallax Collecting Satellite and also a reference to the ancient Greek astronomer Hipparchus of Nicaea, who is noted for applications of trigonometry to astronomy and his discovery of the precession of the equinoxes.

The Science Programme of the European Space Agency is a long-term programme of space science and space exploration missions. Managed by the agency's Directorate of Science, The programme funds the development, launch, and operation of missions led by European space agencies and institutions through generational campaigns. Horizon 2000, the programme's first campaign, facilitated the development of eight missions between 1985 and 1995 including four "cornerstone missions" – SOHO and Cluster II, XMM-Newton, Rosetta, and Herschel. Horizon 2000 Plus, the programme's second campaign, facilitated the development of Gaia, LISA Pathfinder, and BepiColombo between 1995 and 2005. The programme's current campaign since 2005, Cosmic Vision, has so far funded the development of ten missions including three flagship missions, JUICE, Athena, and LISA. The programme's upcoming fourth campaign, Voyage 2050, is currently being drafted. Collaboration with agencies and institutions outside of Europe occasionally occur in the Science Programme, including a collaboration with NASA on Cassini–Huygens and the CNSA on SMILE.

The European Space Agency (ESA) operates a number of space missions, both individually and in collaborations with other space agencies such as U.S. NASA, Japanese JAXA, Chinese CNSA, as well as space agencies of ESA member states (eg. French CNES, Italian ASI, German DLR, Polish POLSA). ESA organizes its missions into various budgetary programmes. This list follows the divisions of the Science Programme, the FutureEO Programme, and the Space Safety Programme. Missions from other programmes, such as Terrae Novae, FLPP, GSTP, or ARTES, are listed in loosely thematic categories.

The current iteration of ESA's Science Programme is the Cosmic Vision Programme, a series of space science missions chosen by ESA to launch through competitions, similar to NASA's Discovery and New Frontiers programmes. It follows the Horizon 2000 and Horizon 2000+ programmes which launched notable missions such as Huygens (Titan lander), Rosetta (comet orbiter and lander), and Gaia (astrometry telescope). These missions are divided into two categories: "Sun and Solar System", space probes studying the Solar System (eg. Solar Orbiter studying the Sun and JUICE currently on its way to Jupiter) and "Astrophysics", space telescopes contributing to interstellar astronomy (eg. CHEOPS characterising exoplanets and Euclid focused on dark matter and dark energy). The Cosmic Vision Programme will be followed by Voyage 2050.