H₂ excitation diagrams at various deprojected distances Z along the redshifted lobe. They are obtained in slits of width ΔZ = 0.2″ (=28 au). Rotational transitions are labeled at the top of each diagram and were dereddened using the mean extinction A_2.12μm estimated from the 1-0Q(7)/1-0S(5) line ratio. v = 1 levels are plotted in orange and v = 2 in blue. The opened diamond symbols represent the 3σ upper limits of undetected H₂ transitions. Error bars are at 1σ. The gray dashed line is the best fit to the points and the gray area shows the 1σ range. The text at the bottom of each panel gives respectively the deprojected distance Z, the mean extinction A_2.12μm, the excitation temperature T_ex and the hot H₂ column density N(H₂) derived from the fit parameters.