Radial variation of the electron temperatures (T_e([N II]) in dark blue circles, T_e([O II]) in blue squares, T_e([S II]) in light blue diamonds, and T_e([S III]) in blue crosses) as a function of the distance to the ionizing star HD 164492A. Faint points represent individual spaxels, while opaque points show the uncertainty-weighted average of all spaxels within 0.1 pc wide distance bins. Standard deviations are shown as error bars. The extent of the measured Strömgren sphere (Sect. 3.4) is shown by a grey dashed line together with the error as a grey shaded region. The linear fits (slopes can be seen in Eq. (C.4)) to the single temperatures are displayed as dashed lines together with the 3σ uncertainties as shaded regions in the corresponding colors.