Royal Observatory, Cape of Good Hope

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Royal Observatory, Cape of Good Hope
Main building of Royal Observatory, Cape of Good Hope.jpg

Main building of the Royal Observatory, Cape of Good Hope
founding October 20, 1820
IAU code 051
Type Observatory
Coordinates 33 ° 56 '5.4 "  S , 18 ° 28' 38.4"  E Coordinates: 33 ° 56 '5.4 "  S , 18 ° 28' 38.4"  E
place Cape Town
management South African Astronomical Observatory
Website South African Astronomical Observatory

The Royal Observatory, Cape of Good Hope (German Royal Observatory at the Cape of Good Hope ) is the oldest continuously existing scientific facility in South Africa . It was founded in 1820 by the British Board of Longitude and is now the main building of the South African Astronomical Observatory .

The observatory is located on a small hill 5 kilometers southeast of central Cape Town . During the 20th century, a suburb of the city emerged in the area, which was named after the already existing observatory Observatory. The observatory was declared a National Heritage Site in December 2018 and was also the subject of an ICOMOS / IAU case study as a UNESCO World Heritage Site .

history

The observatory 1857
Plan of the observatory building, ca.1840.

The proposal for a southern observatory most likely came from the same group of people who founded the Royal Astronomical Society in the UK. The official establishment took place on October 20, 1820 by a resolution of King George IV of the United Kingdom. It remained a separate entity until 1972 when it was merged with the Johannesburg Observatory to form what is now the South African Astronomical Observatory. The site is now the seat of the South African Astronomical Observatory.

In accordance with its mandate, the main activity of the observatory was astrometry , it was responsible for the publication of many catalogs of star positions. In the 20th century it turned in part to astrophysics , but by the 1950s the lights of Cape Town city had made working on faint objects impossible. Consequently, after a new site in the Karoo - semi-desert looking for. An agreement to make this possible was ratified on September 23, 1970. Even so, several telescopes remained in operation until the 1990s . These are rarely used today, except for public relations 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 achievements in the history of astronomy. The second HM astronomer, Thomas Henderson, with the assistance of his assistant, Lieutenant William Meadows, made the first observations that led to a believable stellar parallax, namely of Alpha Centauri . As the discoverer of stellar parallax , however, he lost priority to Friedrich Wilhelm Bessel , who published his own (later) observations of 61 Cygni before Henderson got around to doing so.

Around 1840, Thomas Maclear re- measured the disputed meridian of Nicolas-Louis de Lacaille and showed that its geodetic measurements were correct, but that the nearby mountains had affected his latitude determinations.

In 1882, David Gill took long exposures of that year's great comet, C / 1882 R1 , showing the presence of stars in the background. This prompted him, in collaboration with JC Kapteyn from Groningen, to carry out the Cape Photographic Survey (CPD) , the first star catalog created using photographic means . In 1886 he proposed an international congress to Admiral Ernest Mouchez of the Paris Observatory to create a photographic catalog of the entire sky. This congress took place in Paris in 1887 and led to the Carte du Ciel project . The Kapobservatory was assigned the zone between the declinations of -40 degrees and -52 degrees. The Carte du Ciel project is considered to be the forerunner of the International Astronomical Union .

In 1897, Frank McClean, a close friend of Gill and a 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, Jakob Karl Ernst Halm , then chief assistant, presented a pioneering paper on star dynamics in which he assumed that the stellar currents discovered by Kapteyn stem from a Maxwellian distribution of the stellar velocities. This publication also contains the first suggestion that stars obey a mass-luminosity relationship .

A later HM astronomer of the 20th century, H. Spencer Jones , was on an international project to determine the solar parallax by observing the asteroid Eros .

In the second half of the 20th century, Alan Cousins ​​established very precise standards for UBV and introduced a widespread system of VRI photometry that enjoyed international recognition for its precision.

In 1977 the occlusion of the star SAO 158687 was observed by Joseph Churms of the former Royal Observatory, these observations provided the confirmation of the rings of Uranus , which Elliot et al. from the Kuiper Airborne Observatory plane. During the 19th century, the observatory was considered the main adviser to the colonial government on scientific matters. It served as a storage place for standard weights and measures of the colony and was responsible for the timekeeping and geodetic survey. A magnetic observatory was built in 1841, but it burned down in the following decade. The observatory also has a long line of meteorological records.

The history of the Royal Observatory has been the subject of several publications.

Astronomers at the Cape of Good Hope

Thomas Henderson . His Majesty's astronomer at the Cape of Good Hope, 1831–1833

The directors of the Royal Observatory were known as His or Her Majesty's Astronomers at the Cape. They were as follows:

Other famous astronomers at the Cape of Good Hope:

building

A heritage survey was carried out in 2011 and a full list of the observatory's buildings was drawn up.

McClean building
  • Main building, completed in 1828. Greek Revival style; Architect John Rennie . Today offices and a remarkable astronomical library are located here.
  • Solar telescope building, 1849 (formerly the 7-inch Merz telescope building). Its dome rotates on cannon balls.
  • Heliometer , 1888 (now with 18-inch reflector). The dome (by Howard Grubb ) was designed for through-air ventilation.
  • McClean, 1896, designed by Herbert Baker as a laboratory (now the Astronomical Museum). Hydraulically driven access floor. Dome by T. Cooke & Sons of York .
  • Astrograph , 1889. Dome by Howard Grubb.
  • Passage instrument 1905 (6 inches). Two collimator and two Mark houses each .
  • Technical building (approx. 1987)
  • Auditorium, originally built as an optical instrument repair shop during World War II.

Telescopes

Historically, the main building contained a Dollond passage instrument 10 feet long and a Thomas Jones 6 foot tall one . These were replaced in 1855 with an 8-inch passage instrument designed by George Biddell Airy , Greenwich Royal Astronomer . The Airy instrument was removed in 1950. Some parts of these telescopes are in the astronomical museum of the observatory.

Victoria refractor
  • 4 inch solar telescope (1875) from Dallmeyer .
  • 6 inch refractor (1882) Howard Grubb.
  • Astrograph, 1889 (13-inch photo and 10-inch guide refractors by Howard Grubb). Used for the Cape Astrograph Zone (see above) and used by F. McClean for spectroscopy .
  • McClean or Victoria refractors (18 "visual, 24" photo, and 8 "guide refractors by Howard Grubb).
  • 6 inch passage instrument 1905. Designed by David Gill and constructed by Troughton & Simms . Is used, among other things, for the southern part of the FK4 fundamental catalog.
  • 18 "reflector from Cox, Hargreaves, and Thomson, 1955. The guide refractor is a 7" Merz.

A Grubb Parsons 40-inch reflector was installed in 1964 but was brought to Sutherland in 1972 .

Astronomical Museum

The former McClean Telescope spectroscopic laboratory was converted into a museum in 1987, keeping the original 19th century facilities. The building still contains the original hydraulic equipment for raising the observation floor and a darkroom that contains samples of darkroom equipment taken from various domes after photography was no longer used. The exhibits include models of telescopes, measuring devices, altazimuth instruments by Dollond (1820) and Bamberg (around 1900), calculating machines, early office equipment, early electronic devices, lenses from early telescopes, including Gill photographic telescopes, a clockwork telescopic drive, a signal pistol , Chemical equipment, etc.

Nature of the area

The location of the Royal Observatory is in Two Rivers Urban Park, a wetland area. The underlying rock is Malmesbury schist with a zone of greywacke and quartzite limestone. Part of the original ecology has been preserved and is home to a variety of animals and plants. It is the northern border of the western leopard toad (Bufo pantherinus) and the only remaining natural habitat of the rare iris , Moraea aristata .

Web links

Commons : Royal Observatory, Cape of Good Hope  - Collection of images, videos and audio files

Individual evidence

  1. ^ Government Notice No. 1404 of 2018. In: greengazette. Retrieved May 17, 2020 (English).
  2. ^ A b Royal Observatory, Cape of Good Hope, Republic of South Africa. In: Portal to the Heritage of Astronomy. Retrieved May 17, 2020 (English).
  3. ↑ PROXIMA - THE NEAREST STAR. In: Mons Mensa Publishing, Cape Town (2008). Retrieved May 17, 2020 (English).
  4. ↑ a b Comparison of Oxygen with Helium Stars. In: Royal Society of London. Retrieved May 17, 2020 (English).
  5. ^ A b Further considerations relating to the systematic motions of the Stars. In: Monthly Notices of the Royal Astronomical Society, Volume 71, Issue 8, June 1911, Pages 610-639. Retrieved May 17, 2020 (English).
  6. ^ The Rings of Uranus - the South African Story. In: Monthly Notes of the Astronomical Society of South Africa, Vol. 64, p. 165-169. Retrieved May 17, 2020 (English).
  7. ^ Monthly review of Astronomy. In: THE OBSERVATORY. Retrieved May 17, 2020 (English).
  8. ^ The Astronomical Museum at SAAO. In: Monthly Notes of the Astronomical Society of South Africa, vol. 69, nos. 1 and 2, p. 20-30. Retrieved May 17, 2020 (English).