Effect of jet rotation on the range of apparent velocities observed in the northern limb (green area), southern limb (blue area) and the central stream (red area) assuming the same intrinsic speeds in these three regions. With a viewing angle θ ~ 18° and α_rot ~ 4°, we expect an effective viewing angle in the range 20–24° for the northern limb stream and in the range 12–16° for the southern limb stream.