Fit of a simulated metal abundance profile for an 8 keV cluster at z = 0.1 for the WFI experiment on Athena. The simulated emission-measure and temperature profiles are, respectively, from Eckert et al. (2012) and Reiprich et al. (2013). The spectra were simulated with a one-temperature model and the abundance was fixed to 0.3 Z_⊙ everywhere. The effective area and background intensity are those from the Athena proposal (Rau et al. 2013); the simulated exposure time is 100 ks. The data points show the best fitting abundances and related statistical errors assuming perfect reproducibility of the background, the dashed lines refer to the systematic uncertainties associated with different levels of reproducibility of the background, namely 1%, 2%, and 5%. At small radii where the source dominates over the background, systematic uncertainties on the latter are of little or no consequence; at large radii, where the background dominates, its reproducibility drives the error budget.