Best-fit orbital solution to the astrometric observations. The orbital trace is the motion of the secondary around the primary (the primary being the brightest in the H-band). The periastron of the secondary is represented by a filled symbol and the line of nodes by a dashed line. The astrometric observations are the red ellipses (of typical size less than 0.2 mas), and the corresponding points along the orbit are the black dots. North is up and east is left.