(1909-2000), crystallographer

James Stanley Hey was born on the 3rd May 1909 in Nelson Lancashire. In 1927 he enrolled at Manchester University to study Physics, where he graduated with first-class honours in 1930. He began to work on X-ray crystallography and later worked on the structure of aluminosilicates, from which he published a joint paper with his supervisor and gained his MSc. Hey became a physics master at Burnley Grammar School until the outbreak of World War II, when he joined the Army Operations Research Group (AORG), where his team were responsible for improving the radar for anti-aircraft guns.

In February 1942 Hey had reports of severe noise jamming of anti-aircraft radars in the 4–8 m range. Realising that the direction of maximum interference seemed to follow the Sun, he checked with the Royal Observatory and found that a very active sunspot was traversing the solar disc. Hey knew that sunspots involved strong magnetic fields and that solar activity was accompanied by streams of charged particles, so he reasoned that regions in the solar atmosphere could be acting as giant, natural magnetrons.

When the V2 bombardment of London began, Hey modified some radar sets to track the missiles. He could predict the impact point to within a few kilometres, with 70 seconds’ warning. Concerned about civilian panic, the Ministry of Home Security refused to issue public warnings – a decision Stanley always regretted. With the V2 radars tipped to an appreciable elevation – 55° – the operators discovered short-duration echoes at a height of 80 km. Hey guessed they were reflections from the ionized trails left by meteors. After hostilities ceased, Hey and his colleagues G S Stewart and S J Parsons arranged the radars at Richmond Park (Surrey), Aldeburgh (Suffolk) and Walmer (Kent) to observe the same region of the upper atmosphere. From the trails, Hey could identify meteor showers and plot their radiants.

After the war with Parsons, Hey set up a Yagi aerial system in Richmond Park to map the Milky Way, Hey's observations concluded that a region in Cygnus fluctuated in intensity on a timescale of less than a minute. This first cosmic radio source eventually proved to be a distant and extremely powerful radio galaxy.

After the War, Hey’s observations of the Sun were followed up by Martin Ryle at Cambridge. To determine the size of the emitting regions on the Sun, Ryle developed a radio interferometer, which led on to aperture synthesis and the great radio arrays of today. Meanwhile, Bernard Lovell at Manchester borrowed one of Hey’s radar sets to observe cosmic-ray showers, though that was soon supplanted by meteor research. To escape the city’s electrical interference, Lovell moved Hey’s equipment to a botanical site in Cheshire by the name of Jodrell Bank.

Hey became Head of the AORG in 1949. He then worked as a researcher at the Royal Radar Establishment at Malvern in 1952, where he also continued his radio astronomical observations. Hey’s ultimate achievement – with his colleagues R L Adgie and H Gent – was a two element interferometer, with dishes 25 m in diameter on a track 1 km long. It was sited at an old airfield at Defford, near Malvern, and provided the first radio positions that approached the accuracy of optical positions (about one arc second). In 1964, a long-baseline interferometry link was set up between Defford and Jodrell Bank, providing resolutions at much finer scales. One of the Defford dishes is still in regular use, as the farthest flung element of the MERLIN array of radio telescopes from 1966 until his retirement in 1969 he was head of the research department.

Upon his retirement Hey and his wife Edna moved to Eastbourne in Sussex, where she suffered from a stroke and Hey withdrew from the scientific world to nurse her full-time at home. He died on the 27th February 2000.