Janusz obtained M.Sc. degree in Astronomy from Warsaw University in 1980 and begun his cereer under the guidance of Slavek Rucinski. Originally, his interest was focused on contact binaries of W UMa type which became the subject of his thesis defended in 1985. In 1986 and 1978 he was a postdoc at the Space Telescope Science Institute, where he familiarized himself with the newly introduced CCD photometry. He quickly mastered it and became one of the world-class specialists in this field. At STScI his interests had shifted to binaries in stellar clusters, on which nearly 100 per cent of his future scientific activity was to be concentrated. In early 90s, as an experienced photometrist, he partook in the launching of the OGLE project whose uncountable discoveries are one of the greatest achievements of Polish science in the last quarter of a century.
Within his own observational project CASE, conducted in collaboration with Carnegie Observatories, he elaborated and implemented a method of age and distance determination for globular clusters based on observations of detached eclipsing binaries, originally proposed by Bohdan Paczynski. With his team he collected a unique set of data enabling the verification of the theory of structure and evolution of Population II stars, and the determination of cluster membership from proper motions. His most important scientific achievement was the removal of a discrepancy between the cosmological age of the universe and the age of the oldest globular clusters.
He published nearly 300 papers and supervised eight Ph.D. students. Poland was represented by him in the SALT Scientific Working Group. In 2007 he obtained a prestigious award „Mistrz” (Master) from the Foundation for Polish Science.
We lost a true Master, an unequalled observer, and a warm and good-hearted friend full of humor. Such will be our memory of him.
personal remembrance by Alex Schwarzenberg-Czerny
