Top: luminosity of H₂ 1–0 S(1) per length along the jet, integrated over 1′′ across the jet, for each exposure. Bottom: Gaussian-fitted centroid velocity of H₂ 1–0 S(1) in spectra averaged across a 1′′ wide pseudo-slit. Correction for uneven slit-illumination was applied to each averaged spectrum (see Appendix A). Absolute velocity calibration is better than 2 km s^-1 in each exposure. Vertical 1σ error bars include the fitting error due to noise, and 0.8 km s^-1 rms instrumental calibration drifts between slicing mirrors (see Sect. 2). Horizontal error bars indicate where spectra were further averaged along the jet to increase S/N.