  Using hyperbolic temporal and spatial cut-offs to define 4d asymptotically
flat spacetimes, we show that supertranslation ambiguities in the asymptotic
fields can all be removed even in the presence of gravitational magnetic
charges. We then show that configurations with different electric and magnetic
four-momenta can be consistently considered in the Mann-Marolf variational
principle. This generalizes the previous result where variations over
asymptotically flat configurations with fixed magnetic four-momenta were
considered. We also express Kerr Taub-NUT metric to the leading and next to
leading order in the Beig-Schmidt form, and compare the asymptotic form with
the tensor harmonics on 3d de Sitter space.
