(a) The positions of STEREO-A and the Earth at 15:30 UT on 2021 October 28 in the HEE coordinate system. (b) The ejecta observed by STEREO-A in the 304 Å passband at 15:28:15 UT. The blue dashed line outlines the bright ejecta. (c) The ejecta observed by STEREO-A in the 304 Å passband at 15:33:15 UT. The gray dashed lines are the cuts chosen for the time-space analysis (see the text in Section 3.1) and the numbers at the end of the dashed lines label the cuts. (d) The time-distance diagrams for Cut 2, Cut 3, Cut 5, and Cut 7 (see Section 3.1 for more details).