Union Observatory


Union Observatory also known as Johannesburg Observatory is a defunct astronomical observatory in Johannesburg, South Africa that was operated between 1903 and 1971. It is located on Observatory Ridge, the city's highest point at 1,808 metres altitude in the suburb Observatory.
The observatory and its former annex, the, are known for the discovery of 6,000 double stars and for Proxima Centauri, made by astronomer Robert Innes. At the observatory, 578 identifications of minor planet were made, a record number at the time. The Minor Planet Center credits the observatory as the site where 147 minor planets were discovered by astronomers Harry Wood, Cyril Jackson, Hendrik van Gent, Ernest Johnson, Ejnar Hertzsprung, Jacobus Bruwer and Joseph Churms .

History

The origins of the observatory began when Theodore Reunert of the South African Association for the Advancement of Science petitioned Alfred Milner Governor of the Transvaal Colony on 29 October 1902 for the establishment of a meteorological and astronomical observatory in Johannesburg. Assistant Colonial Secretary W.H. Moor agreed to the project on 17 December 1902 with the budget increased from £1,350 to £5,629 due to equipment changes.
On 1 April 1903, a new Meteorological Department was temporarily established in Johannesburg. A location was sought for the new observatory and the Johannesburg Town Council made a decision on 12 May 1903, located within the municipal boundaries. The land of eight acres, on a ridge west of the Indian War Memorial, was on the northern boundary of the farm Doornfontein, presently part of the suburb Observatory and was given as a gift by the Bezuidenhout family, with a further two acres sold for £500. The land was given only for the use of science and a road, later called Observatory Avenue, was also to be built close to the site. The observatory building was built and the formal opening took place on 17 January 1905 by Governor Milner, but had no astronomical equipment.
In 1906 it was lent a Hamberg universal instrument by Dr Oskar Backlund. In September 1907 a 9-inch Grubb refractor was now used but repolished in 1908. Mr J. Franklin-Adams gifted the observatory a 10-inch triple O.G. Cooke Star-Camera in 1909. J.B. Rissik, Minister for Lands, permitted the purchase of a 26-inch refracting telescope from Sir Howard Grubb in 1909.
With the formation of the Union of South Africa in 1910, South Africa's two 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 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 ; 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:
Its directors were:
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, as the site of 147 minor planet discoveries, made by the following list of astronomers:
715 Transvaalia22 April 1911 
758 Mancunia18 May 1912 
790 Pretoria16 January 1912 
982 Franklina21 May 1922 
1032 Pafuri30 May 1924 
1096 Reunerta21 July 1928 
1116 Catriona5 April 1929 
1132 Hollandia13 September 1929 
1133 Lugduna13 September 1929 
1165 Imprinetta24 April 1930 
1186 Turnera1 August 1929 
1193 Africa24 April 1931 
1194 Aletta13 May 1931 
1195 Orangia24 May 1931 
1196 Sheba21 May 1931 
1197 Rhodesia9 June 1931 
1225 Ariane23 April 1930 
1226 Golia22 April 1930 
1241 Dysona4 March 1932 
1242 Zambesia28 April 1932 
1243 Pamela7 May 1932 
1244 Deira25 May 1932 
1245 Calvinia26 May 1932 
1246 Chaka23 July 1932 
1248 Jugurtha1 September 1932 

1358 Gaika21 July 1935 
1359 Prieska22 July 1935 
1360 Tarka22 July 1935 
1362 Griqua31 July 1935 
1367 Nongoma3 July 1934 
1368 Numidia30 April 1935 
1383 Limburgia9 September 1934 
1384 Kniertje9 September 1934 
1385 Gelria24 May 1935 
1389 Onnie28 September 1935 
1393 Sofala25 May 1936 
1394 Algoa12 June 1936 
1396 Outeniqua9 August 1936 
1397 Umtata9 August 1936 
1427 Ruvuma16 May 1937 
1428 Mombasa5 July 1937 
1429 Pemba2 July 1937 
1430 Somalia5 July 1937 
1431 Luanda29 July 1937 
1432 Ethiopia1 August 1937 
1456 Saldanha2 July 1937 
1467 Mashona30 July 1938 
1468 Zomba23 July 1938 
1474 Beira20 August 1935 
1490 Limpopo14 June 1936 

1701 Okavango6 July 1953 
1702 Kalahari7 July 1924 
1712 Angola28 May 1935 
1731 Smuts9 August 1948 
1738 Oosterhoff16 September 1930 
1752 van Herk22 July 1930 
1753 Mieke10 May 1934 
1760 Sandra10 April 1950 
1784 Benguella30 June 1935 
1816 Liberia29 January 1936 
1817 Katanga20 June 1939 
1819 Laputa9 August 1948 
1879 Broederstroom16 October 1935 
1885 Herero9 August 1948 
1914 Hartbeespoortdam28 September 1930 
1922 Zulu25 April 1949 
1925 Franklin-Adams9 September 1934 
1945 Wesselink22 July 1930 
1946 Walraven8 August 1931 
1948 Kampala3 April 1935 
1949 Messina8 July 1936 
1986 Plaut28 September 1935 
2019 van Albada28 September 1935 
2025 Nortia6 June 1953 
2066 Palala4 June 1934