Polarimetric mapping of the Moon at a phase angle near the polarization minimum

At small phase angles the light scattered by the Moon reveals a negative polarization branch whose average amplitude is 1%. We present results of polarimetric mappings of the Moon in P min at a phase angle near 11°. The observations were carried out with the Kharkov 50-cm telescope at the Maidanak Observatory (Middle Asia) using a polarizing filter. A thorough calibration of the camera array allows for the reliable detection of significant variations of | P min | over the lunar surface, from 0.2 to 1.6%, at a wavelength of 0.52 μm. The smallest | P min | are characteristic of young bright craters, while the | P min | are the highest for the lunar highland and bright mare areas. The horse-shoe shape of the correlation dependence P min (albedo) is treated with data of our laboratory measurements of powdered surfaces and computer modeling of light scattering by small particles with the DDA (discrete dipole approximation) technique.