In early July 2025, our former colleague János Kelemen, an astronomer, passed away. He joined the Konkol Observatory of the Hungarian Academy of Sciences in 1986 and retired as a research fellow in 2015. He started his professional career observing flare stars and for decades he observed comets and small planets with the Schmidt telescope of the Piszkéstető Observatory. In all, he discovered dozens of fler stars, 11 numbered main-belt planets and one near-Earth asteroid. Asterid (545784) Kelemenjános is named after him. He also observed GRB afterglows. He was instrumental in the introduction of CCD technology in the Institute, and led the installation of the first CCD camera on the Schmidt telescope in 1997. He was the first to use a personal computer at the Konkoly Observatory, first a ZX Spectrum and then a Commodore. He has also made a significant contribution to the public outreach, writing numerous popularisation articles and books. He was a member of the Board of the Hungarian Astronautical Society (MANT) and was its Secretary General from 2004-2009. In 2009 he was awarded the Albert Fonó Medal by MANT. One of his loves was flying, he took aerial photographs of the Csillagda and the Piszkéstető Observatory. May he rest in peace.