Lunar albedo at hydrogen Lyman alpha by the NOZOMI/UVS

The geometric albedo of the Moon at the wavelength of hydrogen Lyman alpha (HLy alpha 121.6 nm) was derived from an imaging observation by the ultravi olet imaging spectrometer (UVS) during the lunar encounter of the NOZOMI sp acecraft. The solar HLy alpha irradiance data measured by the UARS/SOLSTICE at the time of UVS observation were adopted. We obtained an average geomet ric albedo of 5.2 +/- 0.9% for the sunlit region where the WS observed. Our result agrees with the geometric albedos obtained from the observations by Apollo 17 and Astro-2/HUT, though the observation geometry and area are co mpletely different from each other. There exists a significant difference o f the albedos from place to place in the observed lunar surface ranging fro m 2.3 +/- 1.1% to 6.0 +/- 1.0%. It is noted that the observed contrast at t he FUV wavelength is positive to that seen in the visible region.