Lodewijk Woltjer (26 April 1930 - 25 August 2019)

It is with profound sadness that I relay the news that Lodewijk Woltjer, founding President of the European Astronomical Society, former Director General of the European Southern Observatory and father of the VLT, passed away in Geneva on Sunday August 25, 2019 at the age of 89.

He was a giant figure in European Astronomy. His scientific legacy benefits us all and he will be greatly missed.

Below you can find a full obituary by Thierry Courvoisier (EAS President 2010-2017).

Roger Davies, EAS President.

Lodewijk Woltjer 1930-2019

European astronomy would not be world leading without the action of Lodewijk Woltjer over several decades.

Lodewijk -Lo- Woltjer started his scientific life as a chemist. The world of chemistry and geology, however, seemed too narrow for his ambitions. The Universe was to be the scientific ground where he would exercise his intellectual strengths.

His first outstanding contribution was an analysis of the polarisation of the Crab nebula and its implication for the magnetic fields within the nebula. From there his interest moved to the dynamic importance of magnetic fields for the structures of the Crab nebula, but also for those of the Galaxy. Since then supernova remnants and neutron stars remained one subject of constant interest to him, culminating in the large observation programmes swiftly put in place at ESO when supernova 1987A exploded.

When quasars and active galactic nuclei were discovered, and the redshift of 3C 273 was measured revealing it's enormous the luminosity, disputes about the origin of the redshifts erupted. Some doubted that objects as extreme as those suggested by observations could exist; a viewpoint that Lo Woltjer very quickly dismissed. His interest in quasars led him to the realm of high energy astrophysics and radio astronomy, domains that were to help him to interact later very fruitfully with colleagues in space sciences. Cosmology became one of his active interests when he suggested, with Giancarlo Setti, that the cosmological "diffuse" X-ray background could be produced by the superposition of the emission of faint Active Galactic Nuclei. Interestingly, each new field of work led to a new thread in Lo Woltjer's work that winds its way from it's nascence through his whole bibliography. Together these threads build into a broad bundle, a sign of the breadth of his contributions and scientific culture. Reading through some of his papers while writing this text I am confirmed in that Lo Woltjer's contributions are not only broad, they are also deep and they impress by the intelligence and clarity of the arguments developed.

Lo Woltjer's contributions to science would be enough to cast his name among those who leave a memorable contribution to astronomy. But he also shaped astronomy through his institutional contributions. He led the astronomy department of Columbia university in New York from 1964 to 1974, when he became Director General of ESO the European Southern Observatory, first in Geneva and then in Garching bei M√ľnchen. When Lo Woltjer took his function, European astronomy was still struggling to emerge from the deep depression in which the Second World War left European science. Instruments on the continent were no match to their US equivalents. Under Lo Woltjer's leadership the situation reversed completely. He developed in ESO a strong scientific group despite tensions between ESO and national communities fearing that they would lose the little leadership they may have had to a strong, supra-national institution. It is largely due to Lo Woltjer's personality and diplomatic skills that these tensions were eased little by little for the benefit of all. Lo Woltjer also had the foresight to form a group of first rate engineers and to encourage them to explore and experiment with a number of novel technologies and solutions to design original telescopes. The success of this approach became clear when the New Technology Telescope came into operation in 1989. This was paving the way to the Very Large Telescope (VLT), which was to become one of the world most successful astronomical instruments. The political skills of Lo Woltjer were of fundamental importance - together with the originality of the concept of four telescopes that could be configured for interferometry, and the preparation work done by ESO's scientists and engineers - in securing the approval of the project by ESO's Council in 1987. All aspects of the VLT definition and preparation bear his mark.

When Lo Woltjer left ESO in 1987 he continued contributing to the development of the astronomical community through his involvement in the International Astronomical Union, of which he was President 1994-1997 and through the founding of the European Astronomical Society (EAS) in the wake of the fall of the Soviet empire. It is also then that he served as chair of ESA's Space Science Advisory Committee, a position through which he contributed decisively to the design of ESA's Horizon 2000 programme. This programme was instrumental in successfully structuring the scientific ambitions of the European Space Agency and of the associated space science community. He served, among many other functions as chair of the INTEGRAL Science Data Centre's Science Advice Committee in Geneva in the 1990's, a much appreciated support in a difficult local environment.

Lo Woltjer's action for the European astronomical community was complemented by that of his wife of many years, Ulla Demierre Woltjer (1944-2019). Ulla had a thorough knowledge of key individuals in the astronomical community, along with their strengths and sometimes weaknesses. She gave many opportunities for the social contacts without which a community cannot develop, thus complementing Lo's activities. She organised formal and less formal events in Chile, Garching, Geneva, Saint-Michel l'Observatoire and elsewhere, where exchanges on many levels also contributed to shape European astronomy.

Lo Woltjer was a distinctly distinguished European personality, always elegant, cultivated, and a musical connoisseur. This notwithstanding, he went several times camping in the Canadian wilderness alone with his daughter Leonore. His desk was always clear, an image of his mind. He had a strong natural authority, a sharp mind and little patience with nonsense. He left a strong impression on those who came across his path, and a lasting mark on those who shared a segment of their careers with him.

Thierry J.-L. Courvoisier
EAS President (2010 - 2017)