Detection of impact-produced dust clouds near the lunar terminator

Abstract Analysis of observations of unique impact-produced flash near the lunar terminator was performed. Maximal brightness of detected thermal flash is 5.2–5.9 m in R band, mass of impacted meteoroid is about 0.18-28 kg. Height of shadow in the place of meteoroid’s impact was only about 1 km, making it possible observations of impact-produced dust particles ejected to the lunar exosphere through their sunlight-scattering response. We detected two (fast and slow) clouds that were expanding with 3 km/s and 0.1 km/s, respectively. The maximal brightness reached by these fast and slow clouds in R band was 6.7 m and 10 m , respectively. Apparent mass of visible ejecta in fast and slow clouds is constrained to 80-8300 and 6-180 kg, respectively. Fast cloud consists of melt droplets and condensed grains while slow cloud consists of ejected lunar regolith dust particles.