Radial profile of the systematic error ΔZ/Z for Perseus. In the top and centre panels the results obtained through an individual fit of the MOS and pn spectra of each region are shown, following strategy 1 and 2, respectively. In the bottom panel the same profiles are shown for the MOS and pn spectra that are considered jointly in the fitting. The weighted averages of the results are shown, together with their 1σ errors, as the pink and the yellow regions, for strategy 1 and 2, respectively.