Fermi Large Area Telescope Observations of the Cosmic-Ray Induced gamma-ray Emission of the Earth's Atmosphere

Understand

We report on measurements of the cosmic-ray induced gamma-ray emission of Earth's atmosphere by the Large Area Telescope onboard the Fermi Gamma-ray Space Telescope.

• The LAT has observed the Earth during its commissioning phase and with a dedicated Earth-limb following observation in September 2008.
• These measurements yielded 6.4 x 10^6 photons with energies >100MeV and ~250hours total livetime for the highest quality data selection.
• This allows the study of the spatial and spectral distributions of these photons with unprecedented detail.