Average surface brightness of the SNR emission (left) and residual stray-light contamination (right) in units of 10^-13 erg cm^-2 s^-1 arcmin^-2 in the full (0.4–10 keV) energy range. The stray-light emission spectrum is substantially harder, so it has a factor of two higher energy flux for a given photon flux. Surface brightness roughly correlates with the reduction of exposure due to exclusion of the most heavily polluted regions shown in Fig. 2. The contours show equal brightness levels for the extended emission for reference.