Spatial dependence of the O3N2 line ratio ([OIII]λ5007/Hβ·Hα/[NII]λ6584, upper left panel), derived metallicity (from O3N2, following Curti et al. (2017) calibrations, upper right panel), ionization parameter U from the [SIII]λ9069/[SII]λ6716, 30 line ratio (lower left panel) and the metallicity map using the diagnostic by Dopita et al. (2016) (lower right panel). The central regions appear to have higher O3N2 and therefore lower metallicity according to single line ratio diagnostics such as O3N2, but the ionization parameter is one order of magnitude higher than the outer regions of the galaxy. The diagnostic by Dopita et al. (2016) actually predict higher metallicity in those regions and a much larger metallicity gradient. All maps indicate the spaxels with S/N> 3 in all the emission lines involved.