Jet intrinsic speed profile based on the analysis of the jet to counter-jet intensity ratio. The solid black vertical line indicates the transition distance of z = 0.58 ± 0.28 pc (accordingly to B21) with the uncertainties enclosed by the dashed black lines. The bulk of the jet accelerates on sub-parsec scales, concurrently with the parabolic jet expansion. The highest velocity of β = 0.95 ± 0.03 is reached around 1 pc.