Comparison between the best-fit modeled (white contours) and observed (background images) morphology of interstellar comet 2I/2019 Q4 (Borisov) on selected dates. A scale bar of 10″ in length, applicable to all of the four panels, is shown. Equatorial north is up and east is left. See Figure 2 for the position angles of the antisolar direction and the negative heliocentric velocity projected onto the sky plane. The best-fit parameters are listed in Table 3.