  We prove smoothness of the domain of outer communications (d.o.c.) of the
Black Saturn solutions of Elvang and Figueras. We show that the metric on the
d.o.c. extends smoothly across two disjoint event horizons with topology R x
S^3 and R x S^1 x S^2. We establish stable causality of the d.o.c. when the
Komar angular momentum of the spherical component of the horizon vanishes, and
present numerical evidence for stable causality in general.
