Active region NOAA 12957. Overview of the observations from EUI (left column) and AIA (right column). In each panel, the thin blue boxes mark the positions of the artificial slits that are used for generating X − T maps. The white arrow in panel c points to a particular thread that is only visible in EUI. Images shown in all panels are averaged over the corresponding observation time of 1 h. An animated version of this figure is available online.