Mean gas expansion velocity measured for the jet as given in Table A.2. These values were used to invert the lines profiles and compute production rates for all molecules. Filled blue dots show pre-perihelion data and empty black symbols represent post-perihelion observations. The fitted power laws are km s⁻¹ pre-perihelion and km s⁻¹ post-perihelion, with uncertainties of 0.01 km s⁻¹ and 0.03 on the power-law index. For comparison we plot the adopted (water) expansion velocity profile of Hansen et al. (2016) as a red dotted line.