Jasper V. Wall

Jasper Wall, widely respected radio and optical astronomer and the final Director of the Royal Greenwich Observatory, died in Surrey, British Columbia, on 28 March 2024 at the age of 82. He was a major figure in the field of radio cosmology, starting with the 1960s controversy over source counts and the steady-state universe, and became an influential pedagogue in statistical astronomy. He also played a key role in the establishment of the La Palma Observatory.

Jasper Vivian, often Jas to close friends, was born in Exeter, England, on 15 January 1942; the family emigrated to Canada in 1947. He studied Engineering Physics at Queen's University and Electrical Engineering and Radio Astronomy at Toronto. He then departed for Australia in 1966, to start a PhD in astronomy at the Australian National University; Jasper preferred this option to an offer from Cambridge, which would have been purely in radio astronomy. But at the ANU he did benefit in particular from the revolution in Australian radio astronomy, driven especially by Edward Bowen and John Bolton, and marked by the 1963 commissioning of the 64m Parkes Telescope. As well as being the largest such telescope in the world, Parkes had also developed receivers that worked at cm wavelengths, an order of magnitude shorter than competing observatories, particularly the one at Cambridge. Jasper constructed one such receiver at CSIRO in Sydney. By the time of Jasper's 1970 PhD, he had helped to carry out a comprehensive survey of the southern sky, cataloguing the brightest few thousand emitters at 2.7 GHz. He also identified and characterised optical counterparts to these sources. Following his PhD, he moved to Parkes and became assistant astronomer to the Director, John Bolton. By this time, he had married Jenny; they went on to have two children, Matthew and Kristina.

During Jasper's time in Parkes, there was also a major non-astronomical highlight. The collecting area of Parkes meant that it was able to detect the transmissions of the Apollo missions, and for some parts of the day was the only ground station able to do this. As a result, Parkes shared the historic honour of allowing the world to witness the first moonwalk, with Jasper being a key member of the team responsible for keeping the pictures flowing. These events were depicted in the 2000 film "The Dish." This was a well-made drama, but Jasper was often heard to bemoan the fact that his character was played as a sex-starved nerd.

In the 1960s, radio telescopes were having a major impact on cosmology, through the counting of extragalactic sources: Martin Ryle's group in Cambridge had claimed an excess of faint sources that required an evolving model, as opposed to the prediction of Hoyle's steady-state universe. Jasper's PhD results from Parkes showed a weaker excess, though still inconsistent with the steady-state model (a conclusion that dismayed Jasper's PhD examiners, who were all believers in Hoyle's theory). The main factor that changed the cm-wavelength count slope was the contribution of a new population of "flat-spectrum" sources - which in many cases turned out to be the relativistically beamed cores of quasars whose jets pointed near to the line of sight. Following these important results, Jasper was invited to join Ryle's group, where he worked between 1974 and 1979 as a Leverhulme Fellow and a Royal Society Jaffe Research Fellow. His work from this time modelled in more detail the evolving universe required by the Parkes results.

In 1979, Jasper was appointed as Head of the Astrophysics Division of the Royal Greenwich Observatory, then at Herstmonceux. The world of research council administration was far from a complete pleasure, and he came to resent what he saw as bureaucratic interference in scientific matters: his desk acquired a magnetic random decision maker offering the alternatives "yes"; "maybe"; "bomb Swindon". But the move to the RGO opened new horizons in scientific exploitation of the optical instrumentation for which the organisation was responsible. This included the UK's first common-user CCD camera, installed on the 3.9m Anglo-Australian Telescope in 1981 and used by Jasper to obtain optical counterparts to Parkes radio sources. At this time, the UK was developing its new observatory on La Palma, and Jasper was made Director of the "Isaac Newton Group" of telescopes between 1987 and 1990, living on the island and taking on the major responsibility for commissioning the telescopes and their new suites of instruments (especially the 4.2m William Herschel Telescope, which saw first light in 1987).

With this demanding task successfully accomplished, he returned to the RGO - to Cambridge, since the Particle Physics & Astronomy Research Council had decreed that a move to a university environment was desirable. But this new organisation was not allowed to put down stable roots, and all too soon it became clear that PPARC was determined to close either the RGO or its northern sibling, the Royal Observatory Edinburgh. This period of "Observatory Wars" was deeply unpleasant for colleagues who had previously been collaborators, and it was Jasper's ill fortune to become appointed as RGO Director in 1995, at the height of events. This can hardly have been an appealing prospect, but he was consumed by a sense of loyalty to his staff, and was determined to give them the best outcome from the struggle. But despite his unrelenting efforts, which came at considerable cost to his health, the outcome was negative and the RGO was closed in 1998.

To recover from this trauma, Jasper took up a position as a Visiting Professor at Oxford. Here, he was able to pour his energies into research once again, writing influential papers on unified schemes for modelling radio source populations using relativistic beaming, and on large-scale clustering of radio sources. He also returned to an enthusiasm from his first Cambridge days and in 2003 completed a well-received textbook on Practical Statistics for Astronomers (with Charles Jenkins, Cambridge, 2003).

After five years in Oxford, Jasper decided to return to Canada, and became an Adjunct Professor at the University of British Columbia, Vancouver. Here he was a popular supervisor of students, to whom he had always been an exceptionally supportive mentor. He was also particularly in demand for his lectures on statistics. During this time, he was able to complete a labour of love and publish his historical account of Radio Astronomy in Canada (with Elizabeth Griffin and Richard Jarrell, Springer 2024).