  We theoretically study the observable response of edge currents in two
dimensional cold atom optical lattices. As an example we use Gutzwiller
mean-field theory to relate persistent edge currents surrounding a Mott
insulator in a slowly rotating trapped Bose-Hubbard system to time of flight
measurements. We briefly discuss an application, the detection of Chern number
using edge currents of a topologically ordered optical lattice insulator.
