Magnetic Deflection of 10^20 eV Particles in Galactic and Extragalactic Fields

Charged particles do not point back to their sources exactly; magnetic fields bend them en route, and the bending is computed here for the extreme events. A 1e20 eV proton crossing one kiloparsec of a two-microgauss galactic field is deflected by 1.060e+00 degrees, while iron at the same energy bends by 2.756e+01 degrees, and iron at 6e19 eV over three kiloparsecs bends by 1.378e+02 degrees, effectively erasing source information. Through a nanogauss extragalactic field, treated coherently, a 1e20 eV proton over ten megaparsecs bends by 5.300e+00 degrees and iron over fifty megaparsecs by 6.890e+02 degrees. Proton astronomy at the highest energies is therefore marginally possible for nearby sources, and iron astronomy is not, which matches the observed near-isotropy of the heavy-inferred flux. No density-bound quantity enters the Lorentz force, and none is claimed to. Simulated and computed; not a measurement.