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The first confirmed Perseid lunar impact flash |
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| Authors: | Masahisa Yanagisawa Kouji Ohnishi Hiroshi Masuda Miyoshi Ida Masayuki Ishida |
| Affiliation: | a University of Electro-Communications, Chofu-shi, Tokyo 182-8585, Japan b Nagano National College of Technology, Nagano-shi, Nagano 381-8550, Japan c Ichinomiya High School, Ichinomiya-shi, Aichi 491-8533, Japan d Ogawa Observatory, Ogawa-mura, Nagano 381-3301, Japan e Dynic AstroPark Observatory, Taga-cho, Shiga 522-0341, Japan f Moriyama-shi, Shiga 524-0104, Japan |
| Abstract: | The first confirmed lunar impact flash due to a non-Leonid meteoroid is reported. The observed Perseid meteoroid impact occurred at 18h28m27s on August 11, 2004 (UT). The selenographic coordinates of the lunar impact flash are 48±1° N and 72±2° E, and the flash had a visual magnitude of ca. 9.5 with duration of about 1/30 s. The mass of the impactor is estimated to have been 12 g based on a nominal model with conversion efficiency from kinetic to optical energy of 2×10−3. Extrapolation of a power law size-frequency distribution fitting the sub-centimeter Perseid meteoric particles to large meteoroids suggests that several flashes should have been observed at this optical efficiency. The detection of only one flash may indicate that the optical efficiency for Perseid lunar impact is much lower, or that the slope of the size distribution differs between large meteoroids and typical sub-centimeter meteoric particles. |
| Keywords: | Impact processes Meteoroids Meteors Moon, surface |
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