A catalogue of large solar energetic particle events observed by Solar Orbiter for the first ~ four years of measurements (20202023)

Solar Orbiter (SO) observations provide an unprecedented opportunity to study the evolution of solar energetic particle (SEP) events from different locations within the heliosphere. In this work, we have compiled a catalogue of SEP events based on observations of both electrons and protons from the High Energy Telescope (HET) of the Energetic Particle Detector (EPD) that occurred in 2020 to 2023 during the ascending phase of Solar Cycle 25. A scan of simultaneous So/HET intensity-time observations for ~10 MeV protons and near relativistic (~1 MeV) electrons has been performed. We have identified all enhancements observed above the background levels of these particular channels and surveyed available solar wind data by the SO/ Solar Wind Analyzer (SWA) and the SO/Magnetometer (MAG) during the identified events. Moreover, we employed Velocity Dispersion Analysis (VDA) for protons and electrons and Time-shifting Analysis (TSA) for electrons, alone, with the aim to infer the SEP release times at the Sun. Our resulting catalogue includes 75 SEP events. For each of these events (and for each species), we provide the onset and peak time, the peak flux value and fluence. We also identify the solar associations/sources for the SEP events, by comparing the inferred release times of the SEPs to the related light curves from the SO/Spectrometer/Telescope for Imaging X-rays (STIX), the standard flare list obtained from the GOES X-ray Sensor and their associated coronal mass ejections (CMEs). We find that a significant portion of all SEP events in our sample (48%; 36/75) reached 50 MeV for protons and thus are Space Weather relevant. Finally, a statistical analysis of our observations is presented. We have investigated correlations between peak particle fluxes (for protons and electrons) and event fluences, as well as peak particle fluxes (event fluences), flare magnitude and CME speed. We also calculate the connection angle to the apparent source and identify a subsample of the events that are better connected to the solar event. In addition, the e/p ratio is calculated and a division of the sample based on Fe-rich and 3He-rich events is discussed. Acknowledgement: Research leading to these results has received funding from the Horizon Europe programme project No 101135044 (SPEARHEAD).