The Mini-EUSO instrument is a UV telescope to be placed inside the International Space Station (ISS), looking down on the Earth from a nadir-facing window in the Russian Zvezda module. Mini-EUSO will map the earth in the UV range (300-400. nm) with a spatial resolution of 6.11. km and a temporal resolution of 2.5. μs, offering the opportunity to study a variety of atmospheric events such as transient luminous events (TLEs) and meteors, as well as searching for strange quark matter and bioluminescence. Furthermore, Mini-EUSO will be used to detect space debris to verify the possibility of using a EUSO-class telescope in combination with a high energy laser for space debris remediation. The high-resolution mapping of the UV emissions from Earth orbit allows Mini-EUSO to serve as a pathfinder for the study of Extreme Energy Cosmic Rays (EECRs) from space by the JEM-EUSO collaboration. 

The Mini-EUSO telescope is designed by the JEM-EUSO Collaboration to observe the UV emission of the Earth from the vantage point of the International Space Station (ISS) in low Earth orbit. The main goal of the mission is to map the Earth in the UV, thus increasing the technological readiness level of future EUSO experiments and to lay the groundwork for the detection of Extreme Energy Cosmic Rays (EECRs) from space (Ebisuzaki et al., 2014). Due to its high time resolution of 2.5 μs, Mini-EUSO is capable of detecting a wide range of UV phenomena in the Earth’s atmosphere. In order to maximise the scientific return of the mission, it is necessary to implement a multi-level trigger logic for data selection over different timescales. This logic is key to the success of the mission and thus must be thoroughly tested and carefully integrated into the data processing system prior to the launch. This article introduces the motivation behind the trigger design and details the integration and testing of the logic.

We present the data acquisition and control software for the operation of the Mini-Extreme Universe Space Observatory (EUSO), a space-based fluorescence telescope for the observation of extensive air showers and atmospheric phenomena. This framework has been extensively tested alongside the development of Mini-EUSO and was finalized ahead of the successful launch of the instrument to the ISS on August 22, 2019. The data acquisition, housekeeping, and subsystem control is achieved using custom-designed front-end electronics based on a Xilinx Zynq XC7Z030 chip interfaced with a PCIe/104 CPU module via the integrated Zynq processing system. The instrument control interface is handled using an object-oriented C++ design, which can be run both autonomously and interactively as required. Although developed for Mini-EUSO, the modular design of both the software and hardware can easily be scaled up to larger instrument designs and adapted to different subsystem and communication requirements. As such, this framework will also be used in the upgrade of the EUSO-TA instrument and potentially for the next EUSO-SPB2 NASA Balloon flight. The software and firmware presented are open source and released with detailed and integrated documentation.

We present a Bayesian hierarchical model which enables a joint fit of the ultrahigh-energy cosmic ray (UHECR) energy spectrum and arrival directions within the context of a physical model for the UHECR phenomenology. In this way, possible associations with astrophysical source populations can be assessed in a physically and statistically principled manner. The importance of including the UHECR energy data and detection effects is demonstrated through simulation studies, showing that the effective GZK horizon is significantly extended for typical reconstruction uncertainties. We also verify the ability of the model to fit and recover physical parameters from CRPROPA 3 simulations. Finally, the model is used to assess the fraction of the publicly available data set of 231 UHECRs detected by the Pierre Auger Observatory which are associated with the Fermi-LAT 2FHL catalogue, a set of starburst galaxies, and Swift-BAT hard X-ray sources. We find association fractions of 9.5(-5.9)(+2.4), 22.7(-12.4)(+6.6), and 22.8(-8.0)(+6.6) per cent for the 2FHL, starburst galaxies, and Swift-BAT catalogues respectively.