In the 1950s at the Mullard Radio Astronomy Observatory, Cambridge, he collaborated with M. Ryle in surveys which led to the series of Cambridge catalogues of radio sources. In 1960 he and Ryle developed aperture synthesis. Hewish began to study fluctuating radio sources, and in 1967 his student S. J. Bell identified what proved to be the first signal from a pulsar. Hewish was awarded the 1974 Nobel Prize in Physics, shared with Ryle, for his work on pulsars.