Visual extinction A_V along the Th 28 jet calculated from [Fe II] 1.644/1.257 and 1.644/1.321. The theoretical intrinsic ratio for A_V = 0 from Smith & Hartigan (2006) is shown by the solid line, whereas the empirical intrinsic ratio determined by Giannini et al. (2015) is shown as the dashed line. The error bars are calculated from the RMS errors plus an uncertainty of 30% for the determination of the Einstein A coefficient and an uncertainty of 10% linked with the flux calibration. The extinction A_V (lower panel) is calculated for all positions, showing the ratio value above the theoretical intrinsic [Fe II] ratio.