Abstract
A very energetic cosmic ray of energy about (1.7-2.6) × eV was observed by the Akeno Giant Air Shower Array on 3 December 1993 from the direction of galactic longitude and galactic latitude within an error circle of 1.0° radius. If this cosmic ray were a proton; its origin could be extragalactic. However, the distance of the source cannot be much more than a few times 10 Mpc due to the energy loss during its travel from interactions with universal background radiation.
- Received 12 August 1994
DOI:https://doi.org/10.1103/PhysRevLett.73.3491
©1994 American Physical Society