Context of our observations. Panel a shows a full-disk magnetogram from HMI observed around the midpoint of the raster map acquired by IRIS. The IRIS field of view is outlined with a blue box. The field of view indicated by the red box is enlarged in panel b. Panel c shows the same area as observed with the 171 Å channel of AIA, plotted in logarithmic scaling. Time stamps that correspond to the beginning of the exposure of HMI and AIA are given with the plots. See Sect. 2.1.