The first reliable radio survey of the northern sky, made at the Mullard Radio Astronomy Observatory, Cambridge. Objects in the catalogue are given the prefix 3C. The Catalogue was published in 1959, with a revised version in 1962 which contained 328 sources north of dec. −5°. Many famous objects appear in the 3C catalogue, including the brightest quasar (3C 273); the brightest radio source outside the Solar System, the supernova remnant Cassiopeia A (3C 461); and the brightest extragalactic radio source, Cygnus A (3C 405).