Leiden Southern Station (Hartebeespoort)

1954 – 1978
Terrain run by Pretoria Technicon: 1978 – present

Current Information:
Current  Information
The  Observatory has closed down. The Current Information section is not relevant to this Observatory.

In Brief:
Noted  for:
Variable star observation
Needing  an observing site with a better climate than that available in Holland, an agreement was reached late in 1923 between Leiden and Union (Republic) Observatories, whereby the facilities of the two institutions were made available to each other. In search of light pollution free skies, Leiden moved to Hartebeespoort. In  time light pollution caught up with this site as well and it was  closed down.

Historical background:


  • Due to very close ties with Leiden Observatory in Holland, an agreement  of co-operation was reached in 1923 between the Union and  Leiden Observatories. Astronomers from each establishment were  free to make use of the facilities of the other. Since the night  skies in Transvaal were infinitely better than in Holland, the flow of visiting astronomers was virtually one way. [Moore,p.107;  Van Herk]
  • By 1929 Leiden Observatory decided to send a telescope and  permanent staff to Union Observatory. The telescope, known as the Rockefeller  twin telescope, was only installed in 1938 due to delays.  The South African Government provided funds for a building at  the Union Observatory to house the Rockefeller telescope. The first astronomer was Enjar  Hertzsprung (Hertzsprung – Russel Diagram)
  • The Leiden Observers were concentrating on variable stars. By 1957 they had accumulated 12 000 photographic plates taken  at the Union Observatory.
  • With  the growing light pollution problem in Johannesburg it was decided  in 1954 to establish an outstation at Hartebeespoort.  This became known as the Leiden Southern Station.
  • The agreement was that the Hartebeespoort facility was operated by Leiden Observers, but it was an official out station of the Union  (later Republic) Observatory, and as such came under Finsen’s jurisdiction even though it was virtually outonomous.
  • Some  of the Union observatory instruments were also moved to the site.
  • By  the time of the move to the Hartebeespoort the Flux Collector telescope arrived and was installed at Hartebeespoort.  The flux collector was the first fully automated telescope (what we call today a Go To Telescope) in Southern Africa.  Due to continuing light pollution problems this telescope was moved in1978 to La Silla in Chile.
  • After the Republic Observatory closed down, the Leiden Southern station  continued to operate until it was sold to Pretoria Technikon. [Hilton]

  • Willem de Sitter: Colleague of Einstein, and one of the pioneers  of the Relativity Theory. De Sitter was a personal friend of Innes, from the Union Observatory. Due to their friendship the agreement  to share facilities, which led to the Southern Station, came about. (To my knowledge he never came to South Africa) [Moore, p.107.]
  • Enjar  Hertzsprung: The first astronomer to be sent by Leiden to the Union Observatory. He, independently from Henry Norris Russel,  around 1913, had first put forward the idea that later became known as the Hertzsprung – Russel Diagram. [Mitton]
  • H  van Gent: Variable star observer. He worked mainly on the  Franklin -Adams telescope (property of Union Observatory)
  • Willem van den Bos: He went to Johannesburg (from Leiden) to do double star work. van den Bos stayed and went on to become the Director  of the Union Observatory.
  • A  Wessellink: (1946 – 1950) Superintendent of the station.

Variable star observation.


  • Rockefeller Twin 16 inch Telescope, 1938. (first installed at Union Observatory, moved to Hartebeespoort 1954)
  • Franklin Adams 10 inch telescope (property of Union Observatory. First installed at Union Observatory, moved to Hartebeespoort 1954)
  • Flux Collector 36 inch, 1957 (moved to La Cilla, Chile 1978)


Pictorial  Sources:


  • Hilton T., Presidential Address: Small Observatories and Unusual Telescopes of Gauteng, MNASSA, Vol. 56, Nos. 9 & 10, October 1997.
  • Smits, P., A Brief History of Astronomy in Southern Africa. (Unpublished)
  • Mitton,  J., A Concise Dictionary of Astronomy, 1991, OUP.
  • Moore, P. & Collins, P., Astronomy in Southern Africa, pp.107 – 110.  (General Source)
  • Van  Herk, G., et. al., The Leiden Southern Station, MNASSA, Vol. 47,  Nos. 3 & 4, 1988.

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