Distribution of the H₂ 2.122 μm emission along the jet. Left image: PV diagram of the H₂ 2.122 μm line along the jet axis of Th 28, obtained by integrating the fluxes in the 22 spectral frames over the direction perpendicular to the jet. Logarithmic contours are drawn from 2  ×  10⁻¹⁴ erg s⁻¹ cm⁻² arcsec⁻² Å⁻¹, with an incremental logarithmic step of 0.3 dex. Two central panels show the derived RV_peak and FWHM_in as a function of distance from the source. A vertical line at 5 km s⁻¹ in the RV panel marks possible systemic RV shift for the line; an average value of FWHM_in is 43 km s⁻¹ (vertical line). Right four panels: Spectral profiles across the jet at selected positions within an ±1″ area in the blue and red lobes (black points). The data were fit using a Moffat function (solid line); the derived peak RV and intrinsic FWHM are shown at the top of each panel.