Satellite high energy astrophysics and research gamma-ray bursts were among topics discussed at the Integral/Bart Workshop (IBWS) 2015 held at Karlovy Vary, attended by 40 participants from five countries. Organized by the CAS Institute of Astronomy and other institutions, it was the12th such gathering focusing on high energy astrophysics and supporting ground-based experiments. The April 20-24 workshop included a “Small Satellite Day” designed to bring together scientific experimenters and payload providers with small satellite designers and realizers. Initially, IBWS workshops focused on the work of Institute’s high energy astrophysics group and that of relevant international collaborators, including students. IBWS workshops in recent years promoted regional collaboration in high energy astrophysics emphasizing the interface between satellite projects and ground-based experiments. Space optics has a long tradition in the Czech Republic and Czech scientists in this field have achieved internationally recognized results. The first Czech astronomical x-ray lens was built in 1970.