  We present adaptive optics spectro-imaging observations of the RW Aur jet in
optical forbidden lines, at an angular resolution of 0.4 arcsec. Comparison
with HST data taken 2 years later shows that proper motions in the blueshifted
and redshifted lobes are in the same ratio as their radial velocities, a direct
proof that the velocity asymmetry in this jet is real and not an emissivity
effect. The inferred jet inclination to the line of sight is i = 46 +/- 3
degrees. The inner knot spacing appears best explained by time variability with
at least two modes: one irregular and asymmetric (possibly random) on
timescales of <3-10 yr, and another more regular with ~ 20 yr period. We also
report indirect evidence for correlated velocity and excitation gradients in
the redshifted lobe, possibly related to the blue/red velocity and brightness
asymmetry in this system.
