Disk-resolved photometry of Vesta and Lutetia and comparison with other asteroids

While a clear anti-correlation is observed between reflectance and steepness of phase function for V, S and C asteroids, Lutetia shows an anomalous photometric behavior, presenting both a low reflectance and a flat phase curve, and hence cannot be grouped with other spectral classes here considered. This behavior is similar to some X-type asteroids ground-observed at low phase angles and is consistent with a chondritic composition of its surface.