NELIOTA: First temperature measurement of lunar impact flashes

¹ IAASARS, National Observatory of Athens, 15236 Penteli, Greece
e-mail: bonanos@astro.noa.gr
² Scientific Support Office, Directorate of Science, European Space Research and Technology Centre (ESA/ESTEC), 2201 AZ Noordwijk, The Netherlands
³ Chair of Astronautics, Technical University of Munich, 85748 Garching, Germany
⁴ Department of Physics, University of Crete, 71003 Heraklion, Greece

Received: 16 October 2017
Accepted: 2 January 2018

Abstract

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 ten flashes detected, for which we find temperatures in the range ~1600 to 3100 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.