Connection of coronal voids to the chromosphere. The upper panel shows an intensity image of the region of interest as recorded by HRI_Lya on 2021 February 23 at 16:58:55, with the same FOV and within about a quarter-hour of the snapshots shown in Fig. 1. The contour lines are the same as in Fig. 1, outlining the coronal voids. The lower panel shows a cut through the image along the blue line in the Ly-α image. Plotted is the intensity in the HRI_Lya (red) and HRI_EUV (orange) channels. To reduce the noise, the cuts have been averaged in the y-direction over 10 pixels. The dark coronal void is seen in the cut in Ly-α as well as in the EUV at 174 Å (vertical blue lines indicate the extent of the void intersected by the cut). See Sect. 3.2 for details.