16–17 January 2021 CME as observed by the SOHO/LASCO/C2 (top row) and STEREO-A/COR2 coronagraphs (bottom row), with running-difference images taken on 17 January. The angular separation between the two spacecraft at that epoch was about 56° (see also Fig. 2). The LASCO/C2 difference frames (FOV: 2–6 R_⊙) have been obtained via subtraction between the two frames acquired at the times given at the bottom of each panel. The COR2 difference frames (FOV: 2–15 R_⊙) are distributed by the official STEREO mission website. The sequence shows first the propagation in the LASCO/C2 FOV (top) followed by the subsequent propagation in the COR2 FOV (bottom).