colonial observatories came under the control of the Minister of the Interior. With the removal of the meteorological functions, the observatory was renamed Observatory of the Union of South Africa (Union Observatory) on 1 April 1912. It became the Republic Observatory in 1961. Well remembered for the quality of its Directors, work done on minor planets and the discovery of Proxima Centauri, growing light pollution problems in Johannesburg led to its closure in 1971–1972. The Observatory's buildings at 18a Gill Street, Observatory, Johannesburg, still exist. At that time the South African government decided to amalgamate all astronomical research into one body, which later became known as the South African Astronomical Observatory (SAAO); it has its headquarters in Cape Town and has Sutherland as its outstation. The main Cape telescopes were moved to Sutherland, and the Radcliffe Observatory at Pretoria was also dismantled. The main-belt asteroid 1585 Union, discovered by Ernest Johnson in 1947, was named for the Union observatory. Name changes Union Observatory went through a number of name changes: 1903–1909: Transvaal Meteorological Department 1909–1912: Transvaal Observatory 1912–1961: Union Observatory 1961–1971: Republic Observatory Directors Its directors were: 1903–1927: Robert Innes 1927–1941: Harry Edwin Wood 1941–1956: Willem Hendrik van den Bos 1957–1965: William Stephen Finsen 1965–1971: Jan Hers (1915–2010) Leiden Southern Station The Leiden Southern Station () was a collaboration between the Dutch Leiden Observatory and Union Observatory. From 1938 to 1954 it was an annex to the Union Observatory, and was moved to Hartbeespoort in 1954 due to light pollution. It operated until 1978. Discoveries List of discovered minor planets The Minor Planet Center credits Union Observatory ("Johannesburg"), as the site of 147 minor planet discoveries, made by the following list of astronomers: Harry Edwin Wood Cyril Jackson Hendrik van Gent Ernest Leonard Johnson Ejnar Hertzsprung Jacobus Albertus Bruwer Joseph Churms References External links Astronomical observatories in South Africa Buildings and structures in Johannesburg Defunct astronomical observatories