  We report the first scientific results from the NELIOTA (NEO Lunar Impacts
and Optical TrAnsients) project, which has recently begun lunar monitoring
observations with the 1.2-m Kryoneri telescope. NELIOTA aims to detect faint
impact flashes produced by near-Earth meteoroids and asteroids and thereby help
constrain the size-frequency distribution of near-Earth objects in the
decimeter to meter range. The NELIOTA setup, consisting of two fast-frame
cameras observing simultaneously in the $R$ and $I-$bands, enables - for the
first time - direct analytical calculation of the flash temperatures. We
present the first 10 flashes detected, for which we find temperatures in the
range ~1,600-3,100 K, in agreement with theoretical values. Two of these
flashes were detected on multiple frames in both filters and therefore yield
the first measurements of the temperature drop for lunar flashes. In addition,
we compute the impactor masses, which range between ~100 g and ~50 kg.
