Abstract

In the remote deserts of Utah, at a location selected for clear air and remoteness from the lights of civilization is the Fly's Eye, a group of "compound eye" light detectors with photomultipliers for facets. It watches the night sky for the light made by the most energetic cosmic rays as they enter the upper atmosphere. Physicists using the Fly's Eye have found an exciting new result, the upper energy limit of cosmic rays. And they have also observed something else, something entering the atmosphere from the direction of the Swan