12-20 July 2017
Asia/Seoul timezone
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BEXCO - Room F(201/202/203/204)

[CRI090] Implications for space-based UHECR observation from UV background light measurements by JEM-EUSO pathfinders



Primary authors



JEM-EUSO (Extreme Universe Observatory onboard Japanese Experiment Module) is a next-generation space-based UHECR observation project. The scientific objectives of the mission stem from enhanced capability of detecting extensive air shower events by fluorescence technique from Space. Accurate measurements of energy spectrum and arrival direction distributions of UHECRs require the determination of the exposure. It involves trigger efficiency, observational duty cycle during UHECR observations and error determination in subsequent data analysis. UV light in the night time atmosphere affects these quantities. This light originates from terrestrial and extraterrestrial sources, including man-made light, airglow emission, starlight, moonlight, zodiacal light etc. It acts as a background for UHECR observations. During the JEM-EUSO pathfinder missions, we have carried out measurements of UV background light by operating prototype telescopes on a balloon and on the ground. EUSO-Balloon achieved one-night stratospheric flight in 2014 in the region of Timmins (Canada), while EUSO-TA has been operated at the site of the Telescope Array Experiment since 2015. In addition, follow-up pathfinder missions; EUSO-SPB and Mini-EUSO are scheduled to be operated on a Superpressure Balloon developed by NASA and in the Russian Zvezda Module onboard the International Space Station, respectively. They are designed to measure UV background light to provide a larger amount of data in various conditions. In the present contribution, we summarize our program of UV background light measurements by JEM-EUSO pathfinders based on available data at the time of Conference. We discuss the scheme to determine exposures for space-based UHECR observations as well as possible spin-off study of the atmospheric science on airglow emission.