Sensitivity of full-sky experiments to large scale cosmic ray anisotropies

Understand

The two main advantages of space-based observation of extreme energy ($\gtrsim5\times10^{19}$ eV) cosmic rays (EECRs) over ground based observatories are the increased field of view and the full-sky coverage with nearly uniform systematics across the entire sky.

• The former guarantees increased statistics, whereas the latter enables a clean partitioning of the sky into spherical harmonics.
• The discovery of anisotropies would help to identify the long sought origin of EECRs.
• We begin an investigation of the reach of a full-sky space-based experiment such as EUSO to detect anisotropies in the extreme-energy cosmic-ray sky compared to ground based partial-sky experiments such as the Pierre Auger Observatory and Telescope Array.