  We study several properties of some new charges of asymptotically flat
spacetimes. These dual supertranslation charges are akin to the magnetic large
$U(1)$ charges in QED. In this paper we find the symmetries associated with
these charges and show that the global dual supertranslation charge is
topological because it is invariant under globally defined, smooth variations
of the asymptotic metric. We also exhibit spacetimes where the charge does not
vanish and we find dynamical processes that interpolate between regions with
different values of these charges.
