SH⁺ absorption spectra obtained toward Sgr B2(M) with the 7-pixel array CHAMP+ at the APEX telescope. The equatorial offset position of each pixel relative to Sgr B2(M) is given in the bottom left corner of each panel. In each panel, the dotted line shows the continuum level as measured over the emission/absorption-free channels, and the red curve is the spectrum predicted by the T_rot = T_CMB model described in Sect. 4.1. All spectra are plotted in main-beam brightness temperature scale.