The 4C Array is a cylindrical paraboloid radio telescope at the Mullard Radio Astronomy Observatory, near Cambridge, England. It is similar in design to the Molonglo Observatory Synthesis Telescope. It is 450 m long, 20 m wide, with a second, moveable element. The first large aperture synthesis telescope (1958), it was also the first new instrument to be built at Lord's Bridge, after the Observatory was moved there in 1957, and needed 64 km (40 mi) of reflector wire. The 4C operated at 178 MHz, and located nearly 5000 sources of the 4C catalogue published in 1965 and 1966, which helped establish the evolution of the radio galaxy population of the universe. The telescope is now inoperable.