Equivalent luminosity-weighted single stellar population values of age (upper panel), metallicity (central panel) and α-enhancement (lower panel) obtained in the five long-slit sections, as function of the distance to NGC 3311. Labels in the upper panel identify each radial bin. The shaded yellow regions indicate the range of SSP parameters that would result if systematic residual effects in the sky subtraction at the level of ≤±2% were present (see Sect. 3.1 for details).