Klaas Sjoerds de Boer (16 November 1941 – 15 March 2022[1]) was a Dutch astronomer and astrophysicist as well as Professor at the University of Bonn.

De Boer studied astronomy and physics at the University of Groningen and obtained his PhD there along with Stuart Pottasch on Interstellar Absorption Lines in the Ultraviolet.

From 1978 to 1981 he was a research associate at the Astronomy Department of the University of Wisconsin (USA) in Madison.

He became 1986 full Professor of Astronomie at the Sternwarte of the University of Bonn, successor of Hans Schmidt.

[4] De Boer was Member and chairman of several committees, among them International Ultraviolet Explorer Programme Committee of the ESA (1986–1994), of the Gutachterausschusses Verbundforschung Astronomie und Astrophysik of the DLR (1991–1993 and 1995–2001), the Science Advisory Group of Gaia-Project (1998–2000)[5] and of the Board of Directors of the international journal Astronomy & Astrophysics (2001–2011).