  We report magnetization and neutron scattering measurements of the half-doped
compound La$_{1.5}$Sr$_{0.5}$CoO$_4$, which exhibits a checkerboard pattern of
charge ordering below ~800K. In the antiferromagnetically-ordered phase below
\~40K the spins are found to be canted in the ab plane. The spin excitation
spectrum includes spin-wave excitations with a maximum energy of 16 meV, and
diffuse magnetic modes at energies around 30 meV.
