Continuum intensity I_c (at 1565 nm) of NOAA 12045 (top) and leading spot of NOAA 12049 (bottom) normalized to the quiet-Sun continuum (I_c,qs) as observed with the GREGOR Infrared Spectrograph (GRIS) on April 24, 2014 and May 3, 2015, respectively. The red squares denote the center of each sunspot: (x,y) = (125″,−309″) for NOAA 12045 and (x,y) = (73″,−83″) for NOAA 12049. The red arrow points toward the center of the solar disk. The areas enclosed by the blue dashed rectangles have been used for calibration purposes (e.g., to calculate the normalization factor I_c,qs; see also Sect. 3), while the areas enclosed by the red dashed rectangles indicate the regions that have been analyzed in our work (see Sects. 4.3 and 5). The scanning direction (i.e., direction of movement of the spectrograph slit) was from top to bottom along the y-axis.