Best orbital solution for AB outer orbit for both uncertainty assumptions in the astrometry before 1991. In all panels the solid line corresponds to the best-fit model and the shaded area to the 1σ region. The solid black lines correspond to the best orbital solution assuming small uncertainties (σ ∼ 0.02″) and the blue ones assume large uncertainties (σ ∼ 0.1″). The red dots correspond to the astrometric measurements. The error bars shown in the astrometry before 1991 correspond to the large uncertainty case.