  A family of particles moving within a cone centered on a Kerr black hole is
shown to have SU(1,1)/U(1) dynamical symmetry. This symmetry is used to
identify a global time variable shared by all particles in the family. With
this time variable, Hamilton's equations for the family of particles have the
canonical form of the harmonic oscillator. The SU(1,1)/U(1) dynamical symmetry,
along with the well defined global time variable and observer, assists in
determining the quantization of the motion.
