We present results from a study of p¯p→Wγ+X events utilizing data corresponding to 0.7 fb−1 of integrated luminosity at √s=1.96 TeV collected by the D0 detector at the Fermilab Tevatron Collider. We set limits on anomalous WWγ couplings at the 95% C.L. The one-dimensional 95% C.L. limits are 0.49<κγ<1.51 and −0.12<λγ<0.13. We make the first study of the charge-signed rapidity difference between the lepton and the photon and find it to be indicative of the standard model radiation-amplitude zero in the Wγ system.Received 1 March 2008DOI:https://doi.org/10.1103/PhysRevLett.100.241805©2008 American Physical Society