A measurement of triple gauge boson couplings is presented, based on W-pair
data recorded by the OPAL detector at LEP during 1998 at a centre-of-mass
energy of 189 GeV with an integrated luminosity of 183 pb(-1). After combin
ing with our previous measurements at centre-of-mass energies of 161-183 Ge
V we obtain kappa = 0.97(-0.16)(+0.20), g(1)(z) = 0.991(-0.057)(+0.060) and
lambda = -0.110(-0.055)(+0.058), where the errors include both statistical
and systematic uncertainties and each coupling is determined by setting th
e other two couplings to their Standard Model values. These results are con
sistent with the Standard Model expectations.