Asymptotic U(1) charges at spatial infinity

Large gauge symmetries in Minkowski spacetime are often studied in two distinct regimes: either at asymptotic (past or future) times or at spatial in fi nity. By working in harmonic gauge, we provide a uni fi ed description of large gauge symmetries (and their associated charges) that applies to both regimes. At spatial in fi nity the charges are conserved and interpolate between those de fi ned at the asymptotic past and future. This explains the equality of asymptotic past and future charges, as recently proposed in connection with Weinberg's soft photon theorem.