STEREO-B EUVI 195 Å difference images showing the flare location and the evolution of the circular EIT-wave relative to the nominal magnetic footpoints of STA (red) and STB (blue) during the SEP event on 11 October 2013. Top right: longitudinal positions of STA, STB, and Earth/SOHO and the nominal Parker spirals connecting them to the Sun. The arrow indicates the location of the parent flare, the source of the SEP event. The angular separations between the s/c magnetic footpoints and the flare position are inserted in the upper right corner.