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Jodrell Bank Observatory () in Cheshire, England, hosts a number of radio telescopes as part of the Jodrell Bank Centre for Astrophysics at the University of Manchester. The observatory was established in 1945 by Bernard Lovell, a radio astronomer at the university, to investigate cosmic rays after his work on radar in the Second World War. It has since played an important role in the research of meteoroids, quasars, pulsars, masers and gravitational lenses, and was heavily involved with the tracking of space probes at the start of the Space Age.

The main telescope at the observatory is the Lovell Telescope. Its diameter of makes it the third largest steerable radio telescope in the world. There are three other active telescopes at the observatory; the Mark II, and and 7 m diameter radio telescopes. Jodrell Bank Observatory is the base of the Multi-Element Radio Linked Interferometer Network (MERLIN), a National Facility run by the University of Manchester on behalf of the Science and Technology Facilities Council.

The Jodrell Bank Visitor Centre and an arboretum are in Lower Withington and the Lovell Telescope and the observatory near Goostrey and Holmes Chapel. The observatory is reached from the A535. The Crewe to Manchester Line passes by the site, and Goostrey station is a short distance away. In 2019, the observatory became a UNESCO World Heritage Site.

Early years

Jodrell Bank was first used for academic purposes in 1939 when the University of Manchester's Department of Botany purchased three fields from the Leighs. It is named from a nearby rise in the ground, Jodrell Bank, which was named after William Jauderell, whose descendants lived at the mansion that is now Terra Nova School. The site was extended in 1952 by the purchase of a farm from George Massey on which the Lovell Telescope was built.Lovell, ''The Story of Jodrell Bank''

The site was first used for astrophysics in 1945, when Bernard Lovell used some equipment left over from World War II, including a gun laying radar, to investigate cosmic rays.Lovell, ''The Story of Jodrell Bank'', p. 2 The equipment was a GL II radar system working at a wavelength of 4.2 m, provided by J. S. Hey.Astronomer by Chance, p. 110Gunn, 2005 He intended to use the equipment in Manchester, but electrical interference from the trams on Oxford Road prevented him from doing so. He moved the equipment to Jodrell Bank, south of the city, on 10 December 1945.Lovell, ''The Story of Jodrell Bank'', p. 3 Lovell's main research was transient radio echoes, which he confirmed were from ionized meteor trails by October 1946.Lovell, ''The Story of Jodrell Bank'', p. 9 The first staff were Alf Dean and Frank Foden who observed meteors with the naked eye while Lovell observed the electromagnetic signal using equipment. The first time Lovell turned the radar on – 14 December 1945 – the Geminids meteor shower was at a maximum.

Over the next few years, Lovell accumulated more ex-military radio hardware, including a portable cabin, known as a "Park Royal" in the military (see Park Royal Vehicles). The first permanent building was near to the cabin and was named after it.

Jodrell Bank is primarily used for investigating radio waves from the planets and stars.

Searchlight telescope

A searchlight was loaned to Jodrell Bank in 1946 by the army;Lovell, ''The Story of Jodrell Bank'', p. 10 a broadside array, was constructed on its mount by J. Clegg. It consisted of 7 elements of Yagi antennas.Astronomer by Chance, p. 129 It was used for astronomical observations in October 1946.Astronomer by Chance, p. 128

On 9 and 10 October 1946, the telescope observed ionisation in the atmosphere caused by meteors in the Giacobinids meteor shower. When the antenna was turned by 90 degrees at the maximum of the shower, the number of detections dropped to the background level, proving that the transient signals detected by radar were from meteors. The telescope was then used to determine the radiant points for meteors. This was possible as the echo rate is at a minimum at the radiant point, and a maximum at 90 degrees to it. The telescope and other receivers on the site studied the auroral streamers that were visible in early August 1947.Lovell, ''The Story of Jodrell Bank'', p. 15Astronomer by Chance, p. 186

Transit Telescope

The Transit Telescope was a parabolic reflector zenith telescope built in 1947. At the time, it was the world's largest radio telescope. It consisted of a wire mesh suspended from a ring of scaffold poles, which focussed radio signals on a focal point above the ground. The telescope mainly looked directly upwards, but the direction of the beam could be changed by small amounts by tilting the mast to change the position of the focal point. The focal mast was changed from timber to steel before construction was complete.

The telescope was replaced by the steerable Lovell Telescope and the Mark II telescope was subsequently built at the same location.

The telescope could map a ± 15-degree strip around the zenith at 72 and 160 MHz, with a resolution at 160 MHz of 1 degree. (the proposal document for the Lovell Telescope). pp. 4–5 It discovered radio noise from the Great Nebula in Andromeda—the first definite detection of an extragalactic radio source—and the remains of Tycho's Supernova in the radio frequency; at the time it had not been discovered by optical astronomy.

Lovell Telescope

The "Mark I" telescope, now known as the Lovell Telescope, was the world's largest steerable dish radio telescope, in diameter, when it was constructed in 1957; it is now the third largest, after the Green Bank telescope in West Virginia and the Effelsberg telescope in Germany.
Part of the gun turret mechanisms from the battleships and were reused in the telescope's motor system.Lovell, ''The Story of Jodrell Bank'', p. 29 The telescope became operational in mid-1957, in time for the launch of the Soviet Union's Sputnik 1, the world's first artificial satellite. The telescope was the only one able to track Sputnik's booster rocket by radar; first locating it just before midnight on 12 October 1957, eight days after its launch.Lovell, ''The Story of Jodrell Bank'', p. 196Lovell, ''Astronomer by Chance'', p. 262

In the following years, the telescope tracked various space probes. Between 11 March and 12 June 1960, it tracked the United States' NASA-launched Pioneer 5 probe. The telescope sent commands to the probe, including those to separate it from its carrier rocket and turn on its more powerful transmitter when the probe was eight million miles away. It received data from the probe, the only telescope in the world capable of doing so. In February 1966, Jodrell Bank was asked by the Soviet Union to track its unmanned Moon lander Luna 9 and recorded on its facsimile transmission of photographs from the Moon's surface. The photographs were sent to the British press and published before the Soviets made them public.

In 1969, the Soviet Union's Luna 15 was also tracked. A recording of the moment when Jodrell Bank's scientists observed the mission was released on 3 July 2009.

With the support of Sir Bernard Lovell, the telescope tracked Russian satellites. Satellite and space probe observations were shared with the US Department of Defense satellite tracking research and development activity at Project Space Track.

Tracking space probes only took a fraction of the Lovell telescope's observing time and the remainder used for scientific observations including using radar to measure the distance to the Moon and to Venus;Lovell, ''Out of the Zenith'', pp. 197–198Lovell, ''Astronomer by Chance'', pp. 277–280 observations of astrophysical masers around star-forming regions and giant stars; observations of pulsars (including the discovery of millisecond pulsars and the first pulsar in a globular cluster); observations of quasars and gravitational lenses (including the detection of the first gravitational lensLovell, ''Astronomer by Chance'', pp. 297–301 and the first Einstein ring). The telescope has also been used for SETI observations.

Mark II and III telescopes

The Mark II is an elliptical radio telescope, with a major axis and a minor axis of . It was constructed in 1964. As well as operating as a standalone telescope, it has been used as an interferometer with the Lovell Telescope, and is now primarily used as part of the MERLIN project.
The Mark III telescope, the same size as the Mark II, was constructed to be transportablePalmer and Rowson (1968) but it was never moved from Wardle, near Nantwich, where it was used as part of MERLIN. It was built in 1966 and decommissioned in 1996.

Mark IV, V and VA telescope proposals

The Mark IV, V and VA telescope proposals were put forward in the 1960s through to the 1980s to build even larger radio telescopes.

The Mark IV proposal was for a diameter standalone telescope, built as a national project.

The Mark V proposal was for a moveable telescope. The concept of this proposal was for a telescope on a railway line adjoining Jodrell Bank, but concerns about future levels of interference meant that a site in Wales would have been preferable. Design proposals by Husband and Co and Freeman Fox, who had designed the Parkes Observatory telescope were put forward.

The Mark VA was similar to the Mark V but with a smaller dish of and a design using prestressed concrete, similar to the Mark II (the previous two designs more closely resembled the Lovell telescope).Lovell, ''Jodrell Bank Telescopes''

None of the proposed telescopes was constructed, although design studies were carried out and scale models were made, partly because of the changing political climate, partly to the financial constraints of astronomical research in the UK and it became necessary to upgrade the Lovell Telescope to the Mark IA, which overran in terms of cost.

Other single dishes

A 50 ft (15 m) alt-azimuth dish was constructed in 1964 for astronomical research and to track the Zond 1, Zond 2, Ranger 6 and Ranger 7 space probes and Apollo 11. After an accident that irreparably damaged the 50 ft telescope's surface, it was demolished in 1982 and replaced with a more accurate telescope, the "42 ft". The 42 ft (12.8 m) dish is mainly used to observe pulsars, and continually monitors the Crab Pulsar.

When the 42 ft was installed, a smaller dish, the "7 m" (actually 6.4 m, or 21 ft, in diameter) was installed and is used for undergraduate teaching. The 42 ft and 7 m telescopes were originally used at the Woomera Rocket Testing Range in Australia. The 7 m was originally constructed in 1970 by Marconi Company.

A Polar Axis telescope was built in 1962. It had a circular 50 ft (15.2 m) dish on a polar mount,Lovell, ''Jodrell Bank Telescopes'', p. 232 and was mostly used for moon radar experiments. It has been decommissioned. An reflecting optical telescope was donated to the observatory in 1951Pullan, ''A history of the University of Manchester 1951–73'', p. 37 but was not used much, and was donated to the Salford Astronomical Society around 1971.

MERLIN

The Multi-Element Radio Linked Interferometer Network (MERLIN) is an array of radio telescopes spread across England and the Welsh borders. The array is run from Jodrell Bank on behalf of the Science and Technology Facilities Council as a National Facility. The array consists of up to seven radio telescopes and includes the Lovell Telescope, the Mark II, Cambridge, Defford, Knockin, Darnhall, and Pickmere

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