Metallicity distributions. Left: Histograms of the metallicity values for the full sample and for each pointing coloured in purple, blue, green, and yellow, respectively. Right: [Fe/H] values as a function of the elliptical radius scaled with R_e, represented as black dots. The black solid line represents the result of a Gaussian process regression analysis using a Gaussian kernel and taking into account an intrinsic scatter; the grey band indicates the corresponding 1σ confidence interval. The histogram on the right side represents the metallicity distribution of the full sample.