Survey area of about 1200 square degrees in the M 63, M 51, M 101, and NGC 6503 filament region. The filled circles show the suggested satellites of the principal galaxies in the chain of groups, shown as squares. The crosses show other galaxies with distances from 5 to 10 Mpc that are not associated with the filament. The dwarf galaxies discovered by us are shown by asterisks. The red symbols correspond to early-type galaxies (T < 0), while the blue symbols represent late-type ones. The small and large circles around the principal galaxies indicate their virial radius, R_vir, and the zero-velocity radius, R₀.