  We present an event generator for the process $pp\to \ell\nu_\ell\gamma$ at
next-to-next-to-leading order (NNLO) in QCD and matched to the PYTHIA8 parton
shower. The calculation makes use of the GENEVA framework, which combines a
resummed calculation obtained via Soft-Collinear Effective Theory (SCET) with
the fixed-order result. We validate the NNLO accuracy of our results by
comparing predictions for inclusive quantities with an independent fixed-order
calculation, and then present the resummed 0-jettiness spectrum at
next-to-next-to-leading logarithmic (NNLL$'$) accuracy. Finally, we compare our
predictions against data collected by the ATLAS experiment at the Large Hadron
Collider during its 7 TeV run, finding good agreement.
