Left panel: spectra extracted from the region with a radius of 0.8° shown in Fig. 1, encompassing the majority of the nebula emission. The fit parameters given in Table 2 for analyses A and B both agree well with the previously reported spectrum (Aharonian et al. 2006b). Right panel: comparison of spectra extracted from the regions of 0.8° and 0.4° radii shown in Fig. 1 together with a spectrum of HESS J1826–130 (Angüner et al. 2017). All spectra are shown with a best-fit model of a power law with exponential cut-off.