  The Telescope Array Collaboration recently reported the detection of a
cosmic-ray particle, "Amaterasu", with an extremely high energy of
$2.4\times10^{20}$ eV. Here we investigate its probable charge and the locus of
its production. Interpreted as a primary iron nucleus or slightly stripped
fragment, the event fits well within the existing paradigm for UHECR
composition and spectrum. Using the most up-to-date modeling of the Galactic
magnetic field strength and structure, and taking into account uncertainties,
we identify the likely volume from which it originated. We estimate a
localization uncertainty on the source direction of 6.6\% of $4\pi$ or 2726
deg$^2$. The uncertainty of magnetic deflections and the experimental energy
uncertainties contribute about equally to the localization uncertainty. The
maximum source distance is 8-50 Mpc, with the range reflecting the uncertainty
on the energy assignment. We provide sky maps showing the localization region
of the event and superimpose the location of galaxies of different types. There
are no candidate sources among powerful radio galaxies. An origin in AGNs or
star-forming galaxies is unlikely but cannot be completely ruled out without a
more precise energy determination. The most straightforward option is that
Amaterasu was created in a transient event in an otherwise undistinguished
galaxy.
