Integrated intensities and examples of spectra of Mg II k (a) and Mg II h (b) from the first nine rasters taken into account for the analysis. Time runs from the beginning of the first raster made at 08:40:00 UT. The wavelength scales Δλ are relative to the line center wavelengths λ₀ (Table 1). The blue horizontal lines indicate the section from which line profiles were taken into the analysis. In order to achieve a sufficient visibility of both Mg II spectral lines in the spectra at the disk edge, limb and prominence, specific intensities for solar_Y below 550 arcsec (white dotted horizontal line) were decreased by the factor of 0.3.