The 4C Array is a cylindrical paraboloid radio telescope

Radio telescope

A radio telescope is a form of directional radio antenna used in radio astronomy. The same types of antennas are also used in tracking and collecting data from satellites and space probes...

 at the Mullard Radio Astronomy Observatory

Mullard Radio Astronomy Observatory

Mullard Radio Astronomy Observatory is home to a number of large aperture synthesis radio telescopes, including the One-Mile Telescope, 5-km Ryle Telescope, and the Arcminute Microkelvin Imager...

. It is similar in design to the Molonglo Observatory Synthesis Telescope

Molonglo Observatory Synthesis Telescope

The Molonglo Observatory Synthesis Telescope is a radio telescope operating at 843 MHz. It is operated by the School of Physics of the University of Sydney...

. It is 450 m long, 20 m wide, with a second, moveable element (now mostly removed; some of it is still visible, beyond COAST). The first large aperture synthesis telescope (1958), it was also the first new instrument to be built at Lord's Bridge, after the Observatory

Mullard Radio Astronomy Observatory

Mullard Radio Astronomy Observatory is home to a number of large aperture synthesis radio telescopes, including the One-Mile Telescope, 5-km Ryle Telescope, and the Arcminute Microkelvin Imager...

 was moved there in 1957, and needed 64 km (39.8 mi) of reflector wire (since removed). The 4C operated at 178 MHz (1.7 m), and located nearly 5000 sources of the 4C (4th Cambridge) catalogue

Fourth Cambridge Survey

The Fourth Cambridge Survey is an astronomical catalogue of celestial radio sources as measured at 178 MHz using the 4C Array. It was published in two parts, in 1965 and 1967 , by the Radio Astronomy Group of the University of Cambridge...

 published in 1965 and 1966, which helped establish the evolution of the radio galaxy population of the universe. The telescope is now inoperable.

It is flanked to the northwest by the Cosmic Anisotropy Telescope

Cosmic Anisotropy Telescope

The Cosmic Anisotropy Telescope CAT was a three-element interferometer for cosmic microwave background radiation observations at 13 to 17 GHz, based at the Mullard Radio Astronomy Observatory. In 1995, it was the first instrument to measure small-scale structure in the cosmic microwave background...

 enclosure and to the south by the One-Mile

One-Mile Telescope

The One-Mile Telescope at the Mullard Radio Astronomy Observatory is an array of radio telescopes designed to perform aperture synthesis interferometry.- History :The One Mile Telescope was completed by the Radio Astronomy Group of Cambridge...

 and Half-Mile Telescope

Half-Mile Telescope

The Half-Mile Telescope was constructed in 1968 at the Mullard Radio Astronomy Observatory with two more aerials being added in 1972, using donated dishes . Two of the dishes are fixed, while two are moveable and share the One-Mile's rail track; to obtain information from the maximum number of...

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