Mean directions of the proper motion vectors in the blue-shifted lobe (top panel) and in the red-shifted lobe (bottom panel). The proper motion track of the protostar is marked by the red line and its current location by the red cross. Clearly, the more distant the knot group is from the protostar, the more distant (to the north-east) the intersection of its mean direction is with the track. The protostar is moving towards the south-west.