& $2900\pm400$ & $9000\pm200$ & $9600\pm200$ & 1\
& $700\pm200$ & $10600\pm300$ & $10700^{+300}_{-200}$ & 5\
& $6700\pm800$ & $10800^{+400}_{-300}$ & $12600\pm300$ & 5\
& $9300^{+1200}_{-900}$ & $10700\pm300$ & $9700\pm200$ & 2\
& $2300\pm300$ & $11400\pm400$ & $13400^{+400}_{-300}$ & 6\
& $2100\pm300$ & $10600\pm500$ & $9400\pm200$ & 5\
& $8900^{+1300}_{-1000}$ & $11600\pm400$ & $11100\pm300$ & 5\
& $7500^{+1100}_{-800}$ & $9700\pm300$ & $9300\pm200$ & 2\
& $3000\pm400$ & $13000^{+500}_{-400}$ & $13400\pm400$ & 5\
& $5400^{+2600}_{-1800}$ & $9300^{+100}_{-700}$ & $7900\pm100$ & 1

Physical conditions {#sec:phys_cond}
===================

We derive electron densities and temperatures, [$n_{\rm e}$]{} and [$T_{\rm e}$]{}, using the routine [*temden*]{} from the package [*nebular*]{} [@Shaw_95] in [IRAF]{}[^1]. For each object, we calculate two temperatures from the observed intensity ratios [\[\]]{} $\lambda5755/(\lambda6548+\lambda6584)$ and [\[\]]{} $\lambda4363/(\lambda4959+\lambda5007)$ to characterize the low- and high-ionization regions, respectively. We also derive an average density from the available diagnostic ratios among the following: [\[\]]{} $\lambda3726/\lambda3729$, [\[\]]{} $\lambda6716/\lambda6731$, [\[\]]{} $\lambda5518/\lambda5538$, and [\[\]]{} $\lambda4711/\lambda4740$. We use the default atomic data in [IRAF]{} except for Cl$^{++}$ and O$^+$: for these ions we find densities in better agreement with those obtained from the other diagnostic ratios using the collision strengths of @Krueger_70 and @Tayal_07 and the transition probabilities of @Mendoza_82 and @Zeippen_82.

