After the Berlin Wall was built in 1961, the highly respected Cuno Hoffmeister found himself isolated in his observatory in Sonneberg, which was virtually inaccessible to visitors due to its location close to the GDR border. Nevertheless, after numerous interventions, he and six of his colleagues managed to travel to an international conference in nearby West German Bamberg in 1965, where it became apparent that the numerical stellar model calculations of a Munich group were able to reproduce large parts of the research on variable stars. The 75-year-old founder of his observatory was involuntarily forced into retirement in 1967 and died shortly afterwards. Until the end of the GDR, no Sonneberg astronomer was ever again allowed to travel to Western countries on official business, and, moreover, the observatory did not survive the political transition period of 1990/1991 as a research facility