Astronomische Gesellschaft Katalog (AGK)
Astronomische Gesellschaft Katalog (AGK) is a standard catalogue of star positions. AGK1 was initiated by Friedrich Argelander in 1867, prepared using data from meridian circles at 17 observatories around the world, and published between 1890 and 1954; it listed the positions of some 200,000 stars down to ninth magnitude between declinations 80° and -23°. A second version, AGK2, that used photographic data from Bonn and Hamburg, was started in the 1920s and published between 1951 and 1958. The latest version, AGK3, published in 1975, lists 183,145 stars north of declination -2° and includes both positions and proper motions. All AGK positions are calculated relative to reference stars, 21,499 of which were used for AGK3 and listed in AGK3R.