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Title: Why do Auger and Telescope Array spectra differ above $3e19\,\mathrm{eV}$?
Plain: The two largest cosmic-ray observatories, one in each hemisphere, disagree on how many particles arrive at the very highest energies.
Precise: After cross-calibration of energy scales, the Telescope Array flux above $\sim 3e19\ \mathrm{eV}$ and its suppression energy remain higher than those of the Pierre Auger Observatory. Determine whether the residual difference is instrumental (energy-scale nonlinearity, aperture, atmospheric corrections) or a real dependence on sky direction that would imply a nearby source in the northern sky. Answer: yes or no for a direction-dependent flux, with significance after systematics, evaluated in the declination band seen by both.
Settled by: Measurements in the common declination band with identical detector types at both sites, such as Auger-type surface stations operated at the Telescope Array site.
Kind: well-posed
Answer type: yes-no
References: (empty)
Literature status: contested
Status note: (empty)
Posed since: (empty)