Table 2: Fit parameters obtained for Model A: f and b are the PCTR and the background intensity, relative to the quiet sun average intensity; x and y are the HI and HeI column densities in units of 10¹⁷ cm^-2.
Filament f b x y HeI/HI $\chi^2$

FP1 0. 0.97 4.2 0.2 4.8 (-2) 0.41

0.1 0.78 5.1 0.2 3.9 (-2) 0.65

0.2 0.60 6.5 0.3 4.0 (-2) 1.23

F2 0. 1.14 5.6 0.5 8.4 (-2) 0.74

0.1 0.99 7.0 0.6 8.6 (-2) 1.13

0.2 0.94 9.5 0.9 9.5 (-2) 2.1

F3 0. 0.61 4.7 0.4 7.9 (-2) 0.22

0.1 0.49 7.2 0.6 9. (-2) 0.51

0.2 1.35 19 2.5 1.3 (-1) 3.8

**Table 2:** Fit parameters obtained for Model A: f and b are the PCTR and the background intensity, relative to the quiet sun average intensity; x and y are the HI and HeI column densities in units of 10¹⁷ cm^-2.
Filament	f	b	x	y	HeI/HI	$\chi^2$
FP1	0.	0.97	4.2	0.2	4.8 (-2)	0.41
	0.1	0.78	5.1	0.2	3.9 (-2)	0.65
	0.2	0.60	6.5	0.3	4.0 (-2)	1.23
F2	0.	1.14	5.6	0.5	8.4 (-2)	0.74
	0.1	0.99	7.0	0.6	8.6 (-2)	1.13
	0.2	0.94	9.5	0.9	9.5 (-2)	2.1
F3	0.	0.61	4.7	0.4	7.9 (-2)	0.22
	0.1	0.49	7.2	0.6	9. (-2)	0.51
	0.2	1.35	19	2.5	1.3 (-1)	3.8

Source LaTeX | All tables | In the text

	1 Introduction
	2 Data analysis
	3 Determination of ${\tau _{912}}$
	4 Discussion and conclusions
	References