page_title: Royal Observatory, Cape of Good Hope
section_title: History
hierarchical_section_title: Royal Observatory, Cape of Good Hope / History
caption_attribution_description: Afrikaans: Bouplan van die hoofgebou van die Koninklike Sterrewag aan die Kaap die Goeie Hoop, geleë in Observatory, Kaapstad, deur Charles Piazzi Smyth wat in 1834 by die sterrewag aangesluit het. Soos aangedui was daar vroeër twee teleskoopkoepels op die suidvleuels. English: Plan of the main building of the Royal Observatory, Cape of Good Hope, drawn by C. P. Smyth
context_page_description: The Royal Observatory, Cape of Good Hope, is the oldest continuously existing scientific institution in South Africa. Founded by the British Board of Longitude in 1820, it now forms the headquarters building of the South African Astronomical Observatory.
  The institution was located on a small hill 5 kilometres south-east from the centre of Cape Town. Over the following century a suburb of the city grew up in the area; the suburb was named Observatory after the pre-existing Royal Observatory. It was declared a National Heritage Site in December 2018 and has also been the subject of an ICOMOS/IAU Case Study as a World Heritage Site.
context_section_description: The proposal for a Southern observatory in all likelihood originated among the same group of people who founded the Royal Astronomical Society in the United Kingdom. Its official establishment took place on 20 October 1820 through an Order in Council of King George IV of the United Kingdom. It remained a separate entity until 1972 when it was amalgamated with the Republic Observatory Johannesburg to form the present-day South African Astronomical Observatory. Its site is now the headquarters of the South African Astronomical Observatory.
  In accordance with its mandate, the principal activity of the Observatory was Astrometry and it was over its existence responsible for publishing many catalogues of star positions. In the 20th century it turned in part towards Astrophysics but by the nineteen-fifties the city lights of Cape Town had rendered work on faint objects impossible and a new site in the Karoo semi-desert was sought. An agreement to facilitate this was ratified on 23 September 1970. Nevertheless, several telescopes remained in operation until the 1990s. These are rarely made use of today except for public outreach events. Alan Cousins was the last serious observer to work from the Royal Observatory site.
  The Royal Observatory was responsible for a number of significant events in the history of astronomy. The second HM Astronomer, Thomas Henderson, aided by his assistant, Lieutenant William Meadows, made the first observations that led to a believable stellar parallax, namely of Alpha Centauri. However, he lost priority as the discoverer of stellar parallax to Friedrich Wilhelm Bessel who published his own (later) observations of 61 Cygni before Henderson got around to his.
  Around 1840, Thomas Maclear re-measured the controversial meridian of Nicolas-Louis de La Caille, showing that the latter's geodetic measurements had been correct but that nearby mountains had affected his latitude determinations
  In 1882, David Gill obtained long-exposure photographs of the great comet of that year showing the presence of stars in the background. This led him to undertake in collaboration with J.C. Kapteyn of Groningen the Cape Photographic Durchmusterung, the first stellar catalogue prepared by photographic means. In 1886, he proposed to Admiral A.E.B. Mouchez of Paris Observatory the holding of an international congress to promote a photographic catalogue of the whole sky. In 1887 this congress took place in Paris and resulted in the Carte du Ciel project. The Cape Observatory was assigned the zone between declinations −40° and −52°. The Carte du Ciel is regarded as the precursor of the International Astronomical Union.
  In 1897 Frank McClean, a close friend of Gill's and the donor of the McClean telescope, discovered the presence of oxygen in a number of stars using an objective prism attached to the Astrographic Telescope.
  In 1911, J.K.E. Halm, then the Chief Assistant, put forward a pioneering paper on stellar dynamics in which he hypothesized that the star streams discovered by Kapteyn arose from a Maxwellian distribution of stellar velocities. This paper also contains the first suggestion that stars obey a mass-luminosity relationship.
  A later 20th-century HM Astronomer, H. Spencer Jones, was active in an international project for determining the solar parallax through observations of the minor planet Eros.
  In the second half of the twentieth century Alan Cousins set up very precise southern standards for UBV and introduced a widely used system of VRI photometry that enjoyed international recognition for precision.
  In 1977 the occultation of the star SAO 158687 was observed by Joseph Churms from the former Royal Observatory and these observations provided needed confirmation of the Uranian rings discovered from the Kuiper aeroplane by Elliot et al.
  During the 19th century the Observatory was regarded as the main advisor to the colonial government on scientific matters. it served as the repository for standard weights and measures of the Colony and was responsible for timekeeping and geodetic surveying. A magnetic observat
caption: Plan of the Royal Observatory building, ca 1840.
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