Table 2: Dereddened fluxes of the lines and doublets used in this work, in units of H $\beta =100$ , and associated measure standard deviations in the same units. ^a Fluxes corrected for the SWS apertures.
Line/doublet Flux Standard deviation

Optical slit

[O II] $\lambda$ 372(6+9) 141.54 0.36

[Ne III] $\lambda$ 3869 36.86 0.18

[S III] $\lambda$ 40(69+76) 1.58 0.14

[O III] $\lambda$ 4363 3.67 0.07

[Ar IV] $\lambda$ 4711 0.26 0.07

[Ar IV] $\lambda$ 4741 0.34 0.05

[O III] $\lambda$ 5007 404.79 0.20

[N II] $\lambda$ 5755 0.20 0.03

He I $\lambda$ 5876 11.94 0.04

[S III] $\lambda$ 6312 1.38 0.04

[N II] $\lambda$ 6583 10.69 0.04

[S II] $\lambda$ 6716 12.73 0.04

[S II] $\lambda$ 6731 9.17 0.03

[Ar III] $\lambda$ 7135 9.47 0.03

[O II] $\lambda$ 73(20+30) 3.09 0.05

Integrated fluxes

[O III] $\lambda$ 5007 352.22 12.46

[S IV] $\lambda$ 11 $\mu$ m^a 37.81 9.72

[Ne III] $\lambda$ 16 $\mu$ m^a 56.51 4.75

[S III] $\lambda$ 19 $\mu$ m^a 81.42 13.66

[S III] $\lambda$ 33 $\mu$ m^a 56.23 9.73

[O III] $\lambda$ 88 $\mu$ m 214.47 8.18

**Table 2:** Dereddened fluxes of the lines and doublets used in this work, in units of H $\beta =100$ , and associated measure standard deviations in the same units. ^a Fluxes corrected for the SWS apertures.
Line/doublet	Flux	Standard deviation
Optical slit
[O II] $\lambda$ 372(6+9)	141.54	0.36
[Ne III] $\lambda$ 3869	36.86	0.18
[S III] $\lambda$ 40(69+76)	1.58	0.14
[O III] $\lambda$ 4363	3.67	0.07
[Ar IV] $\lambda$ 4711	0.26	0.07
[Ar IV] $\lambda$ 4741	0.34	0.05
[O III] $\lambda$ 5007	404.79	0.20
[N II] $\lambda$ 5755	0.20	0.03
He I $\lambda$ 5876	11.94	0.04
[S III] $\lambda$ 6312	1.38	0.04
[N II] $\lambda$ 6583	10.69	0.04
[S II] $\lambda$ 6716	12.73	0.04
[S II] $\lambda$ 6731	9.17	0.03
[Ar III] $\lambda$ 7135	9.47	0.03
[O II] $\lambda$ 73(20+30)	3.09	0.05
Integrated fluxes
[O III] $\lambda$ 5007	352.22	12.46
[S IV] $\lambda$ 11 $\mu$ m^a	37.81	9.72
[Ne III] $\lambda$ 16 $\mu$ m^a	56.51	4.75
[S III] $\lambda$ 19 $\mu$ m^a	81.42	13.66
[S III] $\lambda$ 33 $\mu$ m^a	56.23	9.73
[O III] $\lambda$ 88 $\mu$ m	214.47	8.18

Source LaTeX | All tables | In the text

	1 Introduction
	2 Observational data and reduction
	3 Empirical diagnostics
	4 General strategy for model fitting
	5 Simple models
	6 Models with constrained density distribution
	7 Further refining of the models
	8 Sources of energy other than the ionizing flux
	9 Uncertainties in O/H and Ne/O
	10 Conclusion
	References
	Online Material
	Appendix A: Correction of Balmer lines used for dereddening
	Appendix B: Setting the geometric corrections A, B, and K