  A study of W+W- events accompanied by hard photon radiation produced in e+e-
collisions at LEP is presented. Events consistent with two on-shell W-bosons
and an isolated photon are selected from 183pb^-1 of data recorded at
root{s}=189GeV. From these data, 17 W+W-gamma candidates are selected with
photon energy greater than 10GeV, consistent with the Standard Model
expectation. These events are used to measure the e+e- to W+W-gamma
cross-section within a set of geometric and kinematic cuts; sigma{W+W-gamma} =
136+-37+-8 fb, where the first error is statistical and the second systematic.
The photon energy spectrum is used to set the first direct, albeit weak, limits
on possible anomalous contributions to the {W+ W- gamma gamma} and {W+ W- gamma
Z0} vertices:
  -0.070GeV^{-2} < a_0/Lambda^2 < 0.070GeV^{-2},
  -0.13GeV^{-2} < a_c/Lambda^2 < 0.19GeV^{-2},
  -0.61GeV^{-2} < a_n/Lambda^2 < 0.57GeV^{-2}, where Lambda represents the
energy scale for new physics.
