Grey-scale representation of the Hα line. A close-up of the violet part is shown in the bottom panel. The time scale on the y-axis is not conserved. The spectra are sorted by their sequential number from oldest (lowermost) to latest (uppermost). Marks on the left side of the figure point at the special events detected in the iron lines (see Fig. 17). Spectrum denoted by “D” shows an inverse P Cygni profile of the He i 6678 Å  line.