The Radcliffe Telescope is a 74 in (1.9 m) optical/near-infrared reflecting telescope located at the South African Astronomical Observatory in Sutherland, Northern Cape, South Africa. When construction was completed in 1948, the Radcliffe was the largest telescope in the Southern Hemisphere, and the joint-fourth largest in the world. It is currently the second largest in Africa. The telescope is equipped with a range of instruments operating for photometry, spectroscopy and polarimetry. These are used by professional astronomers to conduct a wide range of astronomical research.
History
Origins
John Radcliffe (1650–1714) was an English physician and Member of Parliament; his alma mater was the University of Oxford. He never married and had no heirs, so when he died he bequeathed much of his large fortune to a charitable trust. This Radcliffe Trust funded public projects in and around Oxford, including the Radcliffe Camera and the Radcliffe Infirmary. On the advice of Thomas Hornsby, in 1773 the trust established the Radcliffe Observatory in what was then the northern outskirts of Oxford; it was the second permanent observatory to be established in Britain (after Greenwich Observatory). This observatory carried out astronomical research, initially under the leadership of the University of Oxford's Savilian Professor of Astronomy. In 1839 the Radcliffe Trust began directly funding a Radcliffe Observer to run the observatory, and observing in Oxford continued productively for most of the next century. In 1924 Harold Knox-Shaw became Radcliffe Observer. By this time the observatory was struggling to remain at the forefront of astronomical research, for a number of reasons. The largest telescope in Oxford was a 24 in (61 cm) refractor, but this was no longer a state-of-the-art instrument and had long been eclipsed by large new reflecting telescopes. In particular, astronomers in America now had access to much larger instruments—such as the 60 in (1.5 m) Hale Telescope (completed 1908) and the 100 in (2.5 m) Hooker Telescope (1917). Several factors made Oxford no longer a suitable site for a research observatory. The city had expanded considerably since the eighteenth century; there was now substantial light pollution and the hot air rising from chimneys caused poor seeing. The British weather was also an impediment, with many nights lost to cloud. The neighbouring Radcliffe Infirmary was keen to expand its buildings, and there was no room for the large enclosure that would be required for any new telescope.
Planning In addition to undertaking routine observations, Knox-Shaw began planning for a new telescope and observatory. Before becoming Radcliffe Observer, Knox-Shaw had served at the Helwan Observatory in Egypt, where he came to appreciate the benefits of siting a telescope in an arid area. In 1928 funding for the 200 in (5.1 m) Hale Telescope was approved, which was to be built at Palomar Observatory, California. This telescope would have four times the collecting area of the next largest in the world, and would easily outperform anything that the Radcliffe Observatory could construct. The southern sky is not visible from Palomar, so it was decided to site the new Radcliffe telescope in the Southern hemisphere where it could observe sources that the Hale Telescope could not. Although the case for building a new large telescope in the Southern hemisphere was compelling, initially no funds were available to Knox-Shaw. In 1929, the millionaire philanthropist Sir William Morris, owner of Morris Motor Company and a patron of the Radcliffe Infirmary, offered to buy the grounds and buildings of the Observatory so the Infirmary could expand into them. Morris offered the sum of £100,000 (equivalent to £5.5 million in 2025), which would be sufficient to fund the new Southern hemisphere observatory.
With the offer of funding in place, in 1929 the Radcliffe Trust asked the Astronomer Royal, Sir Frank Dyson, to assess Knox-Shaw's proposal. Dyson was in favour, and convinced the trustees of the merits of the plan. Later that year, Knox-Shaw, Dyson and Sir Arthur Eddington attended a meeting of the British Association in the Union of South Africa (then a dominion of the British Empire). They took this opportunity to examine several possible sites in the country for the new observatory, deciding that the most favourable was one located on a range of hills near the city of Pretoria. The local Municipality of Pretoria was strongly supportive, offering to donate the land and connect it to the water and electricity distribution systems for free. The site occupied an area of 57 acres (23 ha) on the Kiapperkop ridge of hills 4.5 miles (7.2 km) south-east of the city. From February to June 1930, detailed testing of the weather and seeing conditions at the site was carried out by William Herbert Steavenson, on Knox-Shaw's instructions and with logistical support from the municipality; the site was adjudged to be suitable.
Design and construction
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