hide
Free keywords:
instrumentation: detectors; Sun: particle emission; cosmic rays
Abstract:
Context. The Solar Orbiter Metis coronagraph captures images of the solar corona in both visible (VL) and ultraviolet (UV) light. Tracks ascribable to the passage of galactic and solar particles appear in the Metis images. An algorithm implemented in the Metis processing electronics allows us to separate the pixels fired by VL photons from those crossed by high-energy particles. These spurious pixels are stored in cosmic-ray matrices that can be visually analyzed for particle monitoring deep into the spacecraft's interior. This algorithm has been enabled for the VL instrument only, since the process of separating the particle tracks from pixels fired by photons in the UV images was shown to be quite challenging with respect to a quantitative analysis.
Aims: This work is aimed at studying galactic cosmic rays (GCRs) and solar energetic particles (SEPs) with the Metis cosmic-ray matrices in February 2023.
Methods: We compared a visual analysis of Metis cosmic-ray matrices gathered on February 22, 2023, with GCRs only, and on February 25, 2023 with both GCRs and SEPs, to Monte Carlo simulations of the VL instrument during the same days.
Results: We estimated the solar modulation parameter associated with the GCR proton energy spectrum in February 2023. We show that Metis plays the role of monitoring galactic and solar protons. The Metis particle observations are used for the diagnostics of the VL instrument performance and to study the spacecraft inner charging from solar minimum towards the next solar maximum. These achievements have been attained with the benefit of the joint observations of Metis, the Energetic Particle Detector/High Energy Telescope, and near-Earth and Earth-based instruments.
