O-16 - Auger energy spectra are declination-independent from -90 to +44.8 degrees apart from the known dipolar modulation
Region-specific checks: excluding or isolating the Centaurus-region overdensity (24-deg window around RA 201 deg, dec -43 deg) leaves the band spectra consistent within statistical fluctuations; the same holds around NGC 253 and NGC 1068.
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Why this is evidence
A spectrum shaped by a few foreground sources (a branch of H-37, and the explicit rival H-12 argues against) predicts declination-dependent spectral features; a numerous-source-population account (H-12, and extragalactic H-9) predicts the observed sky-uniformity. A dominant heavy Galactic component below the dip (H-21) would also be expected to leave more directional structure than the mild dipole seen.