  Small perturbations of the homogeneous cooling state (HCS) for a low density
granular gas are described by means of the linearized Boltzmann equation. The
spectrum of the generator for this dynamics is shown to contain points
corresponding to hydrodynamic excitations. The corresponding eigenvectors and
eigenvalues are calculated to Navier-Stokes order and shown to agree with those
obtained by the Chapman-Enskog method. The conditions for the hydrodynamic
excitations to dominate all other excitations are discussed.
