Left panel: part of the full-disk Hα line-centre filtergram obtained by BBSO/NST on 18 May 2005. Vertical bar marks the position of the SoHO/SUMER slit. Spectra were obtained only from the part of the slit that is marked by the solid line because the SUMER detector was partially damaged. Right panel: prominence seen as a filament in part of the full-disk observations in the Hα line centre made at the Kanzelhöhe Solar Observatory three days earlier. The two clearly visible Hα features marked by arrows and denoted as NHS and SHS are the northern and southern Hα prominence structures.