Residual significance map for MSH 15−52, in equatorial coordinates (J2000). Results derived with the 3D likelihood analysis with ctools using an excess template as source model are displayed. We apply a convolution with a top-hat kernel of 0.1° radius to reduce statistical fluctuations. The position of MSH 15−52 is indicated by the “×”. Upper panel: distribution of significance values, together with the fit of a normal distribution (red line).