Lunar impact flashes have been observed at collisions of meteoroids against the non-sunlit lunar surface at speeds exceeding 10 ​km ​s. We detected 13 flash candidates between 6.2 and 9.9 in R-magnitude on December 15, 2018 during the Geminids meteor activity. Two or three observatories confirmed eleven of them. We obtained their spectra in the wavelength range between 400 and 870 ​nm. They are continuous and red, with best-fitted single blackbody spectra indicating the temperatures of about 2000–4000 ​K. The temperatures for a few successive movie frames at 16 ​ms or 25 ​ms intervals decrease with time. Incandescent ejecta, consisting of melt droplets or dust, and the radiant floor of an impact crater could be the source of these flashes, except for the initial stages. At the beginning of some flashes, we found an excess of fluxes at short wavelengths of less than about 600 ​nm. The composites of two blackbody spectra may fit the spectra better where their temperatures are about 2000 K and 6000 ​K. The contribution of a high-temperature vapor plume, generated at the very beginnings of the impact phenomena, could be important.

中文翻译：

---

2018年双子座流星雨月球撞击闪光的低色散光谱

当流星体以超过 10 公里/秒的速度撞击非阳光照射的月球表面时，观察到月球撞击闪光。 2018 年 12 月 15 日双子座流星雨活动期间，我们检测到 13 个 R 星等在 6.2 至 9.9 级之间的候选闪光。两三个天文台证实了其中的十一个。我们获得了 400 至 870 nm 波长范围内的光谱。它们是连续的、红色的，最适合的单一黑体光谱表明温度约为 2000–4000 K。几个连续的电影帧的温度以 16 毫秒或 25 毫秒的间隔随时间下降。除初始阶段外，由熔滴或灰尘组成的白炽喷出物以及撞击坑的辐射底板可能是这些闪光的来源。在一些闪光开始时，我们发现小于约 600 nm 的短波长处有过量的通量。两个黑体光谱的合成可能更好地拟合温度约为 2000 K 和 6000 K 的光谱。在撞击现象开始时产生的高温蒸气羽流的贡献可能很重要。