Observations of the Sun in GeV Gamma Rays by CALET on the ISS

The Calorimetric Electron Telescope (CALET) was deployed on the International Space Station in October 2015 and has accumulated over three years of continuous data to date. The calorimeter (CAL) is sensitive to gamma rays with energies above 1 GeV, and the response has been characterized up to hundreds of GeV. In this work we investigate the flux of gamma rays from the Sun. Previous observations with Fermi-LAT have demonstrated a hard spectrum up to 100 GeV in excess of predictions from cosmic-ray interactions in the solar limb, with a dip from ~30 GeV to ~50 GeV. CALET observations can provide a valuable independent measurement of this flux to further investigate these unexpected features. We present a preliminary measurement of the solar GeV gamma-ray flux using the LE-gamma trigger and an investigation of the expected background and significance of the measurement.