Fit of the two coordinates W(t) and N(t) of component C1 of 1928+738. They correspond to the solution with T_p/T_b ≈ 53, M_CS/M_Cg ≈ 1/4, and i_o ≈ 23°. The points are the observed coordinates of component C1 that were corrected for the offsets ΔW ≈ − 70 μas and ΔN ≈ + 210 μas. The VLBI coordinates and their error bars are taken from Kun et al. (2014). The red lines are the coordinates of the component trajectory calculated using the BBH model.