2DARK天文志

Cherenkov Telescopes (as Magic, Hess and Veritas), while pointing
horizontally should reveal also the fluorescence flare tails of nearby
down-going air-showers. Such air-showers, born at higher (tens km) altitudes,
are growing and extending up to lowest atmospheres (EeVs) or up to higher (few
km) quotas (PeVs). Viceversa, as it has been foreseen and only recently
observed, the opposite takes place. Fluorescence Telescopes made for UHECR
detection may be blazed by inclined Cherenkov lights. The geomagnetic splitting
may tag the energy as well as the inclined shower footprint as seen in a recent
peculiar event in AUGER. Additional stereoscopic detection may define the event
origination distance and its consequent primary composition, extending our
understanding on UHECR composition, while unveling a novel tau Neutrino
Astronomy.