Time series of Mg II triplet spectroheliograms for QSEB – 1. The log of the normalized integrated line intensity for Mg II triplet 2798.8 Å line shown by the pink shaded region in Fig. 7g is displayed in the spectroheliograms. A sequence of four rasters is shown, each raster consists of four slit positions marked with r1–r4 at the top. The vertical dotted lines mark the end of each raster. The black vertical lines denote the start and end time of the QSEB and the black horizontal line denotes the location of the QSEB-1.