  Lunar impact flashes have been monitored over the last 20 years for
determining the mass frequency distribution of near-Earth objects in the cm-dm
size range. In this work, using telescopic observations in R and I band from
the NELIOTA database, impact flash temperatures are derived. They are found to
range between approximately 1,300 and 5,800 K. In addition, it is also found
that temperature values appear to have a distribution significantly broader
than a Gaussian function, therefore making it difficult to estimate the impact
flash luminous energy by assigning an average temperature. By measuring the
flash temperatures and assuming a black body emission, here we derive the
energy of the impacts. We also study the potential link of each event to
individual meteoroid streams, which allows us to assign an impact velocity and
therefore constrain the projectile mass. Impactor masses are found to range
between a few to hundreds of grams, while their sizes are just of few
centimetres following a size frequency distribution similar to other studies.
