Abstract

Logarithmic ambiguities in the choice of asymptotically Cartesian coordinates at spatial infinity are discussed. It is shown that they do not affect the definitions of energy-momentum and angular momentum at i°. Thus, from a physical viewpoint, the ambiguities are “pure gauge.” A prescription is given for fixed this gauge freedom for the class of space-times in which the leading-order part of the Weyl tensor satisfies a certain reflection symmetry. This class admits, in all (relatively boosted) rest frames at infinity, a one-parameter family of asymptotically distinct 3-surfaces (generalized 3-planes) on which the trace of the extrinsic curvature falls off faster than usual