Panel a: STB/EUVI 195Å base difference image at 4:27 UT. The grid lines correspond to a 15° Carrington grid. The four regions of activity are marked by numbers. Panel b: combined EUVI and COR1 difference image taken by STA at 2:35 UT. Panel c: combined EUV and coronagraph difference images observed by SOHO/C2 and SDO/AIA at 4:00 UT. CME1 is marked by green arrows for the time when it is overtaken by CME2 (orange arrows).