User:Modest Genius/Radcliffe Telescope

Not to be confused with the Radcliffe 24-inch telescope at University of London Observatory.

Radcliffe Telescope

Location(s)	Sutherland, Northern Cape, South Africa
Coordinates	32°22′44″S 20°48′41″E
Organization	South African Astronomical Observatory
Wavelength	Optical / near-infrared
Built	1938-1948
First light	1948
Telescope style	Ritchey-Chrétien Cassegrain, Coude or Newtonian reflector
Diameter	74 in (1.9 m)
Mounting	Cross-axis equatorial
Enclosure	Turret
Website	SAAO Homepage

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.

<stuff about history of the telescope - construction, move to Sutherland etc>

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. <Give some examples>

History

Origins

John Radcliffe (1652–1714), whose charitable trust funded the Radcliffe Observatory

Further information: Radcliffe Observatory

When he died in 1714, the English physician and Member of Parliament John Radcliffe bequeathed much of his large fortune to a charitable trust (he had never married and had no natural heirs). This Radcliffe Trust funded a number of projects for the public good in and around Radcliffe's alma mater of Oxford, including the Radcliffe Camera and the Radcliffe Infirmary. On the advice of Thomas Hornsby, in 1773 the trust established the Radcliffe Observatory in the then northern outskirts of Oxford; it was the second observatory to be established in Britain. 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 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). It was clear that if the Radcliffe Observatory - and British observational astronomy in general - were to remain at the forefront of research a large new telescope was required.

Equally clear was that this new telescope could not be sited in Oxford. Since the Observatory had been established the city had expanded considerably, and there was now significant light pollution and poor seeing. The British weather was also an impediment, with many nights lost to cloud. Finally, the neighbouring Radcliffe Infirmary was keen to expand its buildings, and there was no room for the large enclosure which would be required for the new telescope.

The Radcliffe Observatory, Oxford

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 Eygpt, where he came to appreciate the benefits of siting a telescope in an arid area.

<expand, mention southern, ESO + CTIO not until 60s. mention observatories at Cape and Johannesburg>

In 1928 funding for the 200 in (5.1 m) Hale Telescope was approved, which was to be built at Palomar Observatory, California. This massive (and extremely expensive) 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. This effectively settled the argument in favour of erecting the new telescope in the Southern hemisphere.

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 a potential solution to this problem was found: 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 £6.5 million in 2024), which would be sufficient to fund the new Southern observatory.

Sir Frank Dyson (left) and Sir Arthur Eddington (right), who helped decide the location of the new 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 in that year, Knox-Shaw, Dyson and Sir Arthur Eddington attended a meeting of the British Association in South Africa. 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 heavily in favour, and offered 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-Shaws instructions and with logistical support from the Municipality; the site was adjudged to be favourable.

<1930 start negotiating with Grubb Parsons, initially for a 72 inch. 1931 sale of the old observatory completed. Legal hearings, which take up to 1934. Then changed to a modified copy of the DDO 74 inch.<Glass1989> Contract signed in 1935 <Glass1978>, precise date is in 1951ASPL....6..170K

Radcliffe Observatory, Pretoria

<blah>

Harold Knox-Shaw retired as Radcliffe Observer in 1950, and was succeeded by A. David Thackeray, who had joined the observatory in 1948 as Chief Assistant to Knox-Shaw. Thackeray had previously worked at the Solar Physics Laboratory, Cambridge and the Mount Wilson Observatory, California, and had collaborated closely with Arthur Eddington. At the time of Thackeray's appointment, there was only one other astronomer on the staff of the Radcliffe Observatory, the Second Assistant David Stanley Evans. Michael Feast was appointed as the new Chief Assistant in 1951, at which point Evans left and was replaced by Adriaan Jan Wesselink.

<More details on Evans at http://aas.org/node/4094 >

In its early years of operation, the telescope suffered from a lack of scientific instrumentation. For over a year the only observations possible were direct photography, and spectroscopy did not become available until 1951. The first spectrograph was a dual-prism medium-resolution instrument which was mounted at the Cassegrain focus, which quickly became the main instrument for observing. In 1959 it became possible to aluminise the primary mirror, which had previously been coated with silver. This enabled observations to be taken at near-ultraviolet wavelengths. Around 1960 the telescope was equipped with a high-resolution spectrograph housed in the Coudé room, and in 1970 another spectrograph was acquired: an image tube spectrograph optimised for low-resolution observations of faint objects.

The main cause of these problems was a lack of funding, which had also limited staff numbers and the amount of observing which could be undertaken. These problems were alleviated in 1951, when the Radcliffe Observatory entered into an agreement with the British Admiralty (who owned the Royal Observatory at the Cape of Good Hope, Cape Town). The Admiralty bought a one third share of the observing time on the Radcliffe Telescope, for the use of astronomers from the Royal Observatory. Some technical staff were also transferred to Pretoria from the Royal Greenwich Observatory, to provide support for visiting astronomers. In 1967, the UK Science Research Council took over the Admiralty's astronomical responsibilities and increased the UK share of the telescope to 50%, which was made available to all UK-funded observers (not just those based in Cape Town).

<stuff> <Funding, Cape observers, British government involvement>

<science stuff should go below, not follow the history>

After he retired, Knox-Shaw had continued to live in South Africa, but died in 1970 at the age of 85. His ashes were scattered on the observatory grounds. In recognition of his leading role in the construction of the telescope, a bronze memorial plaque was installed on the north pier of the telescope. It reads:

IN MEMORIUM
HAROLD KNOX-SHAW
1885-1970
RADCLIFFE OBSERVER, 1924-1950. THROUGH WHOSE LABOURS
THE RADCLIFFE OBSERVATORY AND THIS TELESCOPE
WERE SET UP UNDER THE SOUTHERN SKIES
TO THE LASTING BENEFIT OF ASTRONOMY.

HE HAS LOVED THE STARS TOO TRULY
TO BE FEARFUL OF THE NIGHT

Instruments

The scientific instruments currently available for use on the Radcliffe Telescope are:

Grating spectrograph

<discuss>

GIRAFFE

<discuss>

HIPPO

<discuss>

SAAO CCD

<discuss>

UCT CCD

<discuss>

Scientific research

Pretoria

Used to discover Thackeray's globules

Photos

To be uploaded / edited / incorporated

Star party next to the dome [1]

Scans of old photos on Flickr. User claims copyright, but they must be from 1938 [2]

Image of the telescope in Pretoria [3]

Spectrograph in use in Pretoria. SPL/RAS copyright, but could be fair use? [4]

Harold Knox-Shaw [5]

External links

• Official SAAO website
• Description from the Astronomical Society of Southern Africa
• Pathe newsreel footage from 1938

Category:Telescopes