Comparison of Phobos photometric properties with those of other Solar System bodies. Top: Phobos reflectance ratio (at α = 0.3º over α = 5º) versus geometric albedo compared to the values observed for different classes of asteroids (following the Tholen & Barucci 1989 classification scheme), derived from Belskaya & Shevchenko (2000), and comet 67P (Fornasier et al. 2015). Bottom: figure adapted from Verbiscer et al. (2022) showing the phase integral versus geometric albedo for dark Solar System bodies. The Phobos value derived in this paper from the green filter and using the Hapke modeling of resolved photometry is represented by a red star (uncertainties are within the star symbol). Literature data of Phobos (q = 0.30) from Simonelli et al. (1998) are also reported. We refer to Verbiscer et al. (2022) (their Fig. 11) for the references of the individual phase integral and geometric albedo values of the objects.