Union Observatory also known as Johannesburg Observatory ( 078) is a defunct astronomical

observatory An observatory is a location used for observing terrestrial, marine, or celestial events. Astronomy, climatology/meteorology, geophysical, oceanography and volcanology are examples of disciplines for which observatories have been constructed. His ...

Johannesburg Johannesburg ( , , ; Zulu and xh, eGoli ), colloquially known as Jozi, Joburg, or "The City of Gold", is the largest city in South Africa, classified as a megacity, and is one of the 100 largest urban areas in the world. According to Demo ...

South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring countri ...

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 An observatory is a location used for observing terrestrial, marine, or celestial events. Astronomy, climatology/meteorology, geophysical, oceanography and volcanology are examples of disciplines for which observatories have been constructed. His ...

. The observatory and its former annex, the , are known for the discovery of 6,000

double star In observational astronomy, a double star or visual double is a pair of stars that appear close to each other as viewed from Earth, especially with the aid of optical telescopes. This occurs because the pair either forms a binary star (i.e. a bi ...

s and for

Proxima Centauri Proxima Centauri is a small, low-mass star located away from the Sun in the southern constellation of Centaurus. Its Latin name means the 'nearest tarof Centaurus'. It was discovered in 1915 by Robert Innes and is the nearest-kno ...

, made by astronomer Robert Innes. At the observatory, 578 identifications of

minor planet According to the International Astronomical Union (IAU), a minor planet is an astronomical object in direct orbit around the Sun that is exclusively classified as neither a planet nor a comet. Before 2006, the IAU officially used the term ''minor ...

were made, a record number at the time. The

Minor Planet Center The Minor Planet Center (MPC) is the official body for observing and reporting on minor planets under the auspices of the International Astronomical Union (IAU). Founded in 1947, it operates at the Smithsonian Astrophysical Observatory. Function ...

credits the observatory as the site where 147 minor planets were discovered by astronomers Harry Wood, Cyril Jackson,

Hendrik van Gent Hendrik van Gent (14 September 1899, Pernis – March 29, 1947, Amsterdam)''Album studiosorum Academiæ lugduno-batavæ MDCCCLXXV-MCMXXV'', A. W. Sijthoff, 1925, p. 376 was a Dutch astronomer. He moved to South Africa in 1928 in order to o ...

, Ernest Johnson,

Ejnar Hertzsprung Ejnar Hertzsprung (; Copenhagen, 8 October 1873 – 21 October 1967, Roskilde) was a Danish chemist and astronomer. Career Hertzsprung was born in Frederiksberg, Denmark, the son of Severin and Henriette. He studied chemical engineering at Cop ...

, Jacobus Bruwer and

Joseph Churms This is a list of minor-planet discoverers credited by the Minor Planet Center with the discovery of one or several minor planets (such as near-Earth object, near-Earth and main-belt asteroids, Jupiter trojans and Distant minor planet, distant obj ...

''(see )''.

History

The origins of the observatory began when Theodore Reunert of the South African Association for the Advancement of Science petitioned

Alfred Milner Alfred Milner, 1st Viscount Milner, (23 March 1854 – 13 May 1925) was a British statesman and colonial administrator who played a role in the formulation of British foreign and domestic policy between the mid-1890s and early 1920s. From De ...

Governor of the

Transvaal Colony The Transvaal Colony () was the name used to refer to the Transvaal region during the period of direct British rule and military occupation between the end of the Second Boer War in 1902 when the South African Republic was dissolved, and the ...

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

. 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

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 (2 5/8-inch object glass) by Dr

Oskar Backlund Johan Oskar Backlund (28 April 1846 – 29 August 1916) was a Swedish-Russian astronomer. His name is sometimes given as Jöns Oskar Backlund, however even contemporary Swedish sources give "Johan". In Russia, where he spent his entire career, he ...

. 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 Sir Howard Grubb (28 July 1844 – 16 September 1931) was an optical designer from Dublin, Ireland. He was head of a family firm that made large optical telescopes, telescope drive controls, and other optical instruments. He is also noted for h ...

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 (Union Observatory) on 1 April 1912. It became the Republic Observatory in 1961. Well remembered for the quality of its Directors, work done on

s and the discovery of

, growing

light pollution Light pollution is the presence of unwanted, inappropriate, or excessive use of artificial Visible spectrum, lighting. In a descriptive sense, the term ''light pollution'' refers to the effects of any poorly implemented lighting, during the day ...

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 South African Astronomical Observatory (SAAO) is the national centre for optical and infrared astronomy in South Africa. It was established in 1972. The observatory is run by the National Research Foundation of South Africa. The facility's funct ...

(SAAO); it has its headquarters in

Cape Town Cape Town ( af, Kaapstad; , xh, iKapa) is one of South Africa's three capital cities, serving as the seat of the Parliament of South Africa. It is the legislative capital of the country, the oldest city in the country, and the second largest ...

and has

Sutherland Sutherland ( gd, Cataibh) is a historic county, registration county and lieutenancy area in the Highlands of Scotland. Its county town is Dornoch. Sutherland borders Caithness and Moray Firth to the east, Ross-shire and Cromartyshire (later ...

as its outstation. The main Cape telescopes were moved to Sutherland, and the

Radcliffe Observatory Radcliffe Observatory was the astronomical observatory of the University of Oxford from 1773 until 1934, when the Radcliffe Trustees sold it and built a new observatory in Pretoria, South Africa. It is a Grade I listed building. Today, the obse ...

Pretoria Pretoria () is South Africa's administrative capital, serving as the seat of the Executive (government), executive branch of government, and as the host to all foreign embassies to South Africa. Pretoria straddles the Apies River and extends ...

was also dismantled. The main-belt asteroid

1585 Union 1585 Union, provisional designation , is a dark background asteroid from the outer regions of the asteroid belt, approximately 52 kilometers in diameter. It was discovered on 7 September 1947, by South African astronomer Ernest Johnson at the U ...

, 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 Harry Edwin Wood (3 February 1881 – 27 February 1946) was an English astronomer, director of the Union Observatory in Johannesburg, and discoverer of minor planets. Wood was born in Manchester, graduating from Manchester University in 1902 w ...

* 1941–1956:

Willem Hendrik van den Bos Willem Hendrik van den Bos (25 September 1896 – 30 March 1974) was a Dutch astronomer who worked at the Union Observatory in South Africa and became its director in 1941. He discovered nearly new double stars, made more than astronomical me ...

* 1957–1965:

William Stephen Finsen William Stephen Finsen FRAS (28 July 1905 – 16 May 1979) was a South African astronomer. He discovered a number of double stars and took many photographs of Mars. He developed the Finsen eyepiece interferometer to measure very close double st ...

* 1965–1971: Jan Hers (1915–2010)

Leiden Southern Station

The Leiden Southern Station () was a collaboration between the Dutch

Leiden Observatory Leiden Observatory ( nl, Sterrewacht Leiden) is an astronomical institute of Leiden University, in the Netherlands. Established in 1633 to house the quadrant of Rudolph Snellius, it is the oldest operating university observatory in the world, with ...

and Union Observatory. From 1938 to 1954 it was an annex to the Union Observatory, and was moved to

Hartbeespoort Hartbeespoort, informally also known as "Harties", is a small resort town in the North West Province of South Africa, situated on slopes of the Magaliesberg mountain and the banks of the Hartbeespoort Dam. The name of the town means "gateway of th ...

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: *

* Cyril Jackson *

Ernest Leonard Johnson Ernest Leonard Johnson (1891–1977) was a South African astronomer and a former staff member of the Union Observatory in Johannesburg, South Africa. He is known for the discovery of 18 asteroids between 1946–1951, as well as several comets. ...

Jacobus Albertus Bruwer This is a list of minor-planet discoverers credited by the Minor Planet Center with the discovery of one or several minor planets (such as near-Earth and main-belt asteroids, Jupiter trojans and distant objects). , the discovery of 612,011 nu ...

References

* *

External links

* * {{webarchive , url=https://web.archive.org/web/20080803124314/http://www.saao.ac.za/assa/html/assa_johannesburg_centre.html , date=August 3, 2008 , title=Johannesburg Centre Astronomical observatories in South Africa Buildings and structures in Johannesburg Defunct astronomical observatories