  Motivated by our attempt to understand the question of angular momentum of a
relativistic rotating source carried away by gravitational waves, in the
asymptotic regime near future null infinity of the Kerr metric, a family of
null hypersurfaces intersecting null infinity in shearfree (good) cuts are
constructed by means of asymptotic expansion of the eikonal equation. The
geometry of the null hypersurfaces as well asthe asymptotic structure of the
Kerr metric near null infinity are studied. To the lowest order in angular
momentum, the Bondi-Sachs form of the Kerr metric is worked out. The
Newman-Unti formalism is then further developed, with which the Newman-Penrose
constants of the Kerr metric are computed and shown to be zero. Possible
physical implications of the vanishing of the Newman-Penrose constants of the
Kerr metric are also briefly discussed.
