Absolute calibration of the Clementine UVVIS data:: Comparison with ground-based observation of the Moon

Calibrated Clementine images of the Moon and data from Pieters's absolutized spectrophotometric catalog ate compared. The scales of these two photometric systems are shown to differ greatly: the albedo of the lunar surface at a phase angle of 6 degrees determined from the Clementine data turns out to be a factor of 2.5 higher than that inferred from ground-based photometry. The fact that the lunar-soil samples from the Apollo 16 landing site used for absolute calibration of the Clementine data are not representative may be responsible for the differences between the scales. Maps are constructed (for wavelengths of 0.42, 0.75, and 0.95 mum), which reproduce the distribution of the ratio of the brightnesses determined from telescopic images of the visible lunar hemisphere and from the corresponding Clementine mosaics. The comparison shows fairly good agreement in the details. On the average, the differences are about 10%. The streakiness of the Clementine mosaics are clearly seen in the maps, which is attributable to a low quality of the photometric joining of the data from two one-month imaging series.