Geometry of the disk and fly-by orbit of the RW Aur system in the reference frame of the sky. Light blue indicates the disk, pink indicates the orbit, where the pink dashed line shows the crossing line of the plane of the orbit with the x-y-plane and the periastron (pink dot) is “in front,” meaning closer to us than the x-y-plane. The position angles Ω_d,o, inclinations θ_d,o and the argument of the periapsis of the orbit ω_o are defined consistently with our definition in Figure 1. Note that this coordinate system is left-handed.