Fit of the two coordinates W(t) and N(t) of component C6 of 1928+738. They correspond to the solution with T_p/T_b ≈ 1500, M_BHC6/M_BH4 ≈ 0.3, and i_o ≈ 21°. The points are the observed coordinates of component C6 that were corrected for the offsets ΔW ≈ + 110 μas and ΔN ≈ + 1300 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.