  An analytic calculation of the photon mass gap M of compact U(1)_{2+1} in the
Hamiltonian formalism is performed utilizing the first four Hamiltonian moments
with respect to a one-plaquette mean field state in the plaquette expansion
method. Scaling of M is clearly evident at and beyond the transition from
strong to weak coupling. The scaling behaviour agrees well with the range of
results from numerical calculations.
