MERGED (2b reconcile): duplicate of D-2 - Pierre Auger Observatory UHECR dataset (same Pierre Auger Observatory). Survivor = D-2 (lowest id). Sources S-64, S-67, S-69 repointed to D-2. Retained per move-never-delete.
known_biases: common ~14% absolute fluorescence energy-scale calibration and shared exposure/aperture model; an energy-scale or aperture error moves every Auger flux/spectrum measurement together, so successive Auger spectrum papers are not independent of each other.