Photo: Society members' in front of the Arcminute Microkelvin Imager Large Array at the Mullard Radio Astronomy Observatory (MRAO) in Cambridge.

Society members' enjoyed a visit to the Mullard Radio Astronomy Observatory in Cambridge, site to the discovery of pulsars in 1967. The site has a rich histroy, located a few miles south-west of Cambridge at Harlton on a former ordnance storage site, next to the disused Oxford-Cambridge Varsity railway line. 

The 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. Radio interferometry started in the mid-1940s on the outskirts of Cambridge, but a few years after the construction of the MRAO transferred to the current site at Lord's Bridge.

The observatory was founded under Martin Ryle of the Radio-Astronomy Group of the Cavendish Laboratory, University of Cambridge and was opened by Sir Edward Victor Appleton on 25 July 1957. This group is now known as the Cavendish Astrophysics Group. The site is at a former ordnance storage facility, next to the now-abandoned Cambridge-Bedford railway line. A portion of the track bed of the old line, running nearly East-West for several miles, was used to form the main part of the "5km" radio-telescope and the Cambridge Low Frequency Synthesis Telescope.

The Interplanetary Scintillation Array (also known as the IPS Array or Pulsar Array) is a radio telescope that was built in 1967 at the MRAO built by and operated by the Cavendish Astrophysics Group including Jocelyn Bell and Tony Hewish for detection of pulsars. The instrument originally covered 4 acres (16,000 m²). It was enlarged to 9 acres in 1978, and was refurbished in 1989. The IPS Array has more recently been used to track and help forecast interplanetary weather, and specifically to monitor the solar wind. It is now essentially retired, and has lost a significant fraction of its area, although it is still visible to visitors.

The Observatory is operated by the Cavendish Laboratory, supported by the Science and Technology Facilities Council.

The site is also home to the 32 metre MERLIN (Multi-Element Radio Linked Interferometer Network) receiver,  an interferometer array of radio telescopes spread across England. The array is run from Jodrell Bank Observatory in Cheshire by the University of Manchester on behalf of STFC as a National Facility.

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Photo: The Arcminute Microkelvin Imager - Small Array (AMI-SA).

Photo: Control room for the Half-Mile Telescope, which was constructed in 1968.

Photo: The 1958 4C Array, the first telescope at the observatory, used to make the 4C catalogue.