Recent R-matrix calculations of electron impact excitation rates in O iii are used to calculate electron temperature and density-dependent emission line ratios R1 = I(4363 Å)/I(4960 Å + 5007 Å), R2 = I(1661 Å + 1667 Å)/I(4960 Å + 5007 Å) and R3 = I(2322 Å)/I(1661 Å + 1667 Å), for a range of electron temperatures (7500 ≤ Te ≤ 30 000 K) and densities (104 ≤ Ne ≤ 107 cm−3) applicable to gaseous ne...
