Sketch of the inner region of SS 433. Most (90%) of the infrared continuum comes from a partially resolved central source of typical size ~0.8 mas (central red area). The 10% continuum flux left is produced by a completely resolved background on a larger scale (>15 mas, background area). The Brγ-line-emitting region size is found to be ~1 mas and is dominated by an East-West component, in the direction of the jet (yellow area). The measured position angle of the jet is ~ 80°. The jet profile is unresolved in the transverse direction (<1.2 mas). The intensity profile along the jet axis is best characterized by an emission peaking at the continuum position and decreasing exponentially on a scale of 1.7 mas.