Zdeněk Švestka, co-founder and Editor in Chief of Solar Physics for 38 years passed away on 2 March 2013 at his home in Bunschoten, The Netherlands. With him we lose one of the great defining personalities of twentieth-century solar physics.

Zdeněk was born on 30 September 1925 in Prague, Czechoslovakia. He studied mathematics and physics at Charles University, Prague. After his graduation in 1948, he started working at the Astronomical Observatory at Ondřejov. From 1956 to 1970, he became the head of the newly established Solar Department there. The department flourished with a group of outstanding young researchers and instrumentalists, and became one of the best-equipped solar observatories in Europe. Meanwhile, Zdeněk was also active in the IAU, serving as vice-president, and then president of Commission 10 (Solar Activity) between 1964 and 1970.

It was during the same period that Zdeněk received a letter from Kees de Jager proposing to start a new journal dedicated to the studies of the Sun and Sun-Earth relations. Zdeněk, who was concerned about the lack of attention that the Sun received in other astronomical journals, sent an immediate enthusiastic reply to Kees. The new journal, Solar Physics, was launched in 1966. It quickly became an increasingly influential and successful forum for the solar physics community. For 29 years Kees and Zdeněk were the two co-Editors in Chief of the journal. Later Bob Howard joined them. After Kees’ retirement Zdeněk edited Solar Physics for another ten years, first with Bob Howard and Oddbjørn Engvold, and after Bob’s retirement with Jack Harvey. Even after Zdeněk’s retirement in 2005, the present editorial team profited from his vast editorial experience and insight. Zdeněk was a tireless and most effective editor. He had positive and constructive relation with the publishers of the journal, and he was a great mentor to all of his co-editors.

In 1970, Zdeněk left Czechoslovakia to work at ESTEC in The Netherlands. In the years to follow he worked at the Kiepenheuer Institute in Freiburg, Germany, then moved to the US in 1974, where he worked at American Science and Engineering in Cambridge on the then new Skylab data. While there, inspired by new observations, he completed his high-impact book on Solar Flares, which was published in 1976. In 1977, Zdeněk was offered a position at the Space Research Laboratory in Utrecht, The Netherlands, where he worked up to his retirement and beyond, while keeping his ties with the US and ongoing X-ray experiments there through regular visits to the University of California in San Diego.

Zdeněk’s scientific activities included the organization of the “Quiet Sun Year” with Paul Simon of Paris Observatory, the “Proton Flare Project” aiming for better understanding of the sources of solar energetic particles, which resulted in a successful forecast of a proton event for the launch of a balloon flight (SPARMO). As a result, Zdeněk was awarded the Guggenheim Award in Astronautics in 1968. He organized many scientific conferences, COSPAR and IAU Symposia, and edited many of the publications resulting from these meetings.

Zdeněk’s main scientific interest focused on solar flares. During the Ondřejov years he became an expert in flare spectra. Later he became interested in white-light flares, proton flares, and their radio signatures (type II and IV bursts), which were suggestive of shock-acceleration of particles. He also linked indications for the latter to interplanetary sector boundaries. Data from Skylab, then the Solar Maximum Mission with the Dutch Hard X-ray Imaging Spectrometer instrument onboard, and finally the Yohkoh satellite led to his in-depth studies of X-ray loops and flare signatures. His results included the discovery of very long loops inter-connecting different active regions, even across the Equator, which occasionally showed “sympathetic” activity. He discovered the loop shrinkage phenomenon in combined Hα and X-ray data of (post-) flare loops, supporting the reconnection scenario for flares. He published more than 200 scientific papers, with more than 110 coauthors, that have to date received more than 3200 citations.

The IAU honored Zdeněk by naming a minor planet, discovered by M. Tichý and Z. Moravec in 1998, after him: 17805 Švestka.

Zdeněk’s Solar Physics Memoir paper entitled “Sixty years in solar physics”, was recently published (DOI: 10.1007/s11207-010-9675-4), in which he shared candid insights into his life and career.

He is survived by his wife, solar physicist Lida Švestka-Fritzová, his daughter, son, and grandson, who live in The Netherlands and in the Czech Republic.

L. van Driel-Gesztelyi, J.J. Blom, C. de Jager, O. Engvold, F. Fárník, J.W. Harvey, P. Heinzel, R.F. Howard, J. Leibacher, C.H. Mandrini, T. Sakurai