Left column: maps of N_e determined from [S II] and [N II] lines (upper) and [Cl III] and a T_e = 10 000 K (lower). The electron densities for collisional de-excitation of the [S II] and [Cl III]² D_3∕2 levels for these diagnostics are 3.1 × 10³ and 2.4 × 10⁴ cm⁻³ at 10 000 K respectively. Centre column: maps of T_e determined from [S II] and [N II] lines (upper) and [S III] and a N_e = 1000 cm⁻³ (lower). Right column: maps of T_e for the [O I] lines (upper) and the He I recombination lines (lower).