International audienceEUSO-Balloon is a prototype for the future space telescope JEM-EUSO aiming to detect UV emissions in the Earth's atmosphere (cosmic air showers, meteorites, airglow, etc). It successfully completed its first flight operated by the CNES over Ontario, Canada, in August 2014. One of the main goals is to measure the photoelectron rate performed by its UV camera. These measurements, corrected from noise contamination, are presented including their time variation. a particular emphasis is put on the determination of the statistical and systematic errors using the relative calibration that was made for all the 2304 pixels. Possible improvements of these performances are discussed in the perspective of future flights
