The orbit of the center of mass of components B and C around component A. The observed positions are marked by their error ellipses and lines connecting the observed and calculated position at the time of the observations. Note that these positions are computed from the observed positions of components B and C, and the mass ratio q, which is a free parameter of the model fit. The dash-dotted line indicates the line of nodes, the dashed line the periastron, and the arrow shows the direction of the orbital motion. The two orbits shown are the model with the globally minimum χ², and an almost circular orbit with a longer period of about 80 years.