Union Observatory Explained

Union Observatory
Location:Observatory, Johannesburg, South Africa
Coords:-26.1842°N 28.0742°W
Altitude:1808m (5,932feet)
Closed:1971

Union Observatory also known as Johannesburg Observatory (078) 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 (see).

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.[1] 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.[1]

On 1 April 1903, a new Meteorological Department was temporarily established in Johannesburg.[1] 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.[1] 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.[1] 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.[1] The observatory building was built and the formal opening took place on 17 January 1905 by Governor Milner, but had no astronomical equipment.[1]

In 1906 it was lent a Hamberg universal instrument (2 5/8-inch object glass) by Dr Oskar Backlund.[1] In September 1907 a 9-inch Grubb refractor was now used but repolished in 1908.[1] Mr J. Franklin-Adams gifted the observatory a 10-inch triple O.G. Cooke Star-Camera in 1909.[1] J.B. Rissik, Minister for Lands, permitted the purchase of a 26-inch refracting telescope from Sir Howard Grubb in 1909.[1]

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.[1] With the removal of the meteorological functions, the observatory was renamed Observatory of the Union of South Africa (Union Observatory) on 1 April 1912.[1] 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:

Directors

Its directors were:

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:

important; height: 675px;
22 April 1911 
18 May 1912 
16 January 1912 
21 May 1922 
30 May 1924 
21 July 1928 
5 April 1929 
13 September 1929 
13 September 1929 
24 April 1930 
1 August 1929 
24 April 1931 
13 May 1931 
24 May 1931 
21 May 1931 
9 June 1931 
23 April 1930 
22 April 1930 
4 March 1932 
28 April 1932 
7 May 1932 
25 May 1932 
26 May 1932 
23 July 1932 
1 September 1932 
important; height: 675px;
21 April 1933 
23 April 1930 
29 April 1930 
15 June 1933 
15 June 1933 
17 August 1933 
19 July 1928 
24 March 1934 
19 March 1934 
13 May 1934 
7 May 1934 
19 May 1934 
15 June 1934 
14 July 1934 
14 July 1934 
7 September 1934 
9 September 1934 
9 September 1934 
13 February 1935 
13 June 1934 
13 February 1935 
3 April 1935 
30 April 1935 
3 May 1935 
2 July 1935 
important; height: 675px;
21 July 1935 
22 July 1935 
22 July 1935 
31 July 1935 
3 July 1934 
30 April 1935 
9 September 1934 
9 September 1934 
24 May 1935 
28 September 1935 
25 May 1936 
12 June 1936 
9 August 1936 
9 August 1936 
16 May 1937 
5 July 1937 
2 July 1937 
5 July 1937 
29 July 1937 
1 August 1937 
2 July 1937 
30 July 1938 
23 July 1938 
20 August 1935 
14 June 1936 
important; height: 675px;
21 April 1939 
15 May 1939 
21 August 1946 
22 May 1950 
7 September 1947 
19 June 1930 
3 September 1950 
10 July 1951 
5 July 1948 
9 August 1948 
25 September 1929 
19 August 1935 
3 May 1935 
25 July 1935 
13 July 1953 
7 April 1953 
4 August 1926 
22 July 1930 
16 September 1930 
9 September 1934 
15 June 1939 
28 September 1935 
16 September 1930 
5 May 1935 
29 September 1934 
important; height: 675px;
6 July 1953 
7 July 1924 
28 May 1935 
9 August 1948 
16 September 1930 
22 July 1930 
10 May 1934 
10 April 1950 
30 June 1935 
29 January 1936 
20 June 1939 
9 August 1948 
16 October 1935 
9 August 1948 
28 September 1930 
25 April 1949 
9 September 1934 
22 July 1930 
8 August 1931 
3 April 1935 
8 July 1936 
28 September 1935 
28 September 1935 
6 June 1953 
4 June 1934 
important; height: 595px;
18 May 1926 
28 September 1935 
13 February 1935 
23 March 1950 
28 August 1949 
30 July 1951 
28 September 1935 
19 September 1938 
9 August 1948 
17 September 1930 
31 July 1935 
28 September 1935 
22 August 1949 
13 July 1953 
10 July 1928 
5 September 1937 
28 September 1935 
28 September 1935 
28 September 1935 
31 May 1948 
5 July 1937 
12 July 1936 

References

Notes and References

  1. The history of the Transvaal Observatory. Hers. J.. 1987-02-01. Monthly Notes of the Astronomical Society of South Africa. en. 46. 1–2. 17–19. 0024-8266. |