ИСТИНА

Orbital ultra high energy cosmic ray (UHECR) detector TUS (tracking ultraviolet set-up) is prepared for launching on-board Lomonosov satellite. The TUS space experiment is aimed to study energy spectrum and arrival distribution of UHECR at energy range above 10^20 eV. TUS detector will operate in various UV night atmosphere background. Fast UV flashes (lightning, transient luminous events) are an important part of background. These transient events will effect operation of trigger system and decrease duty cycle of UHECR detectors especially above thunderstorm regions where frequency of lightning could be very high. New measurements of transient events were performed by UV detector on board Universitetsky-Tatiana-2 satellite. Influence of transient luminous events on operation of UHECR detector TUS is discussed.