AGA fit of DoAr21b obtained with the combined model. Left: the upper panels show the parallax after removing proper motions and the contribution of the orbit of DoAr21b. The lower panels show the orbit of DoAr21b after removing proper motions and parallax. The black dots correspond to the observed astrometric data with their error bars. The red crosses indicate the expected position at the observed epochs. The orbit of this companion is plotted as function of the phase orbit. The R.A. and decl. offsets are relative to the estimated barycenter position of the source. Right: the solid line shows the orbit of DoAr21b around the host star. The open circles indicate the estimated positions of DoAr21b with respect to the host star (black star at the center of the orbit), and the red crosses indicate the predicted positions along the orbit at the observed epochs. The red dots indicate the positions of the observed companion. The error bars of these data points are smaller than the size of the dot. There is an excellent agreement between the observed positions and the predicted positions.