(21) Lutetia spectrophotometry from Rosetta-OSIRIS images and comparison to ground-based observations

Abstract: Here we present some preliminary results on surface variegation found on (21) Lutetia from ROSETTA-OSIRIS images acquired on 2010-07-10. The spectrophotometry obtained by means of the two cameras NAC and WAC (Narrow and Wide Angle Cameras) is consistent with ground based observations, and does not show surface diversity above the data error bars. The blue and UV images (shortward 500nm) may, however, indicate a variegation of the optical properties of the asteroid surface on the Baetica region (). We also speculate on the contribution due to different illumination and to different ground properties (composition or, more probably, grain size diversity). In particular a correlation with geologic units independently defined by is evident, suggesting that the variegation of the ground optical properties is likely to be real. [Copyright &y& Elsevier]