Normalized surface brightness profiles of 289P (blue circles) and a field star (black circles), from median-combined W1 image in Visit B (MJD 58860: UT 2020 January 11–12, outbound; Figure 2, left panel). The FWHM of 289P is θ_F = 6﹩\mathop{.}\limits^{{\rm{^{\prime} }}{\rm{^{\prime} }}}﹩6. Linear distances > 40″ are precluded (vertical dashed line) due to the nonuniform background, preventing further profile analysis.