Named in memory of Jiří Horn (1941-1994), an astronomer at the Ondřejov Observatory. He worked in stellar astrophysics, observational astronomy and data reduction, making important contributions to all of them. He was a member of the team that in the late 1960s made the first calculations of the evolution of close binaries with mass loss. He played an important role in the commissioning phase of the 2-m telescope at Ondřejov. He created the user-friendly software SPEFO for the reduction of stellar spectra that is still in use by many astronomers. Name proposed by the discoverers, following a suggestion by P. Koubský, who also prepared the citation.