  Electromagnetic radiation from the quark-gluon plasma (QGP) is an important
observable to be considered in heavy ion collision experiments. I will provide
an update on recent advancements from perturbation theory and quenched lattice
simulations. The resummed next-to-leading order (NLO) emission rate has
recently been decomposed into transverse and longitudinal components, and
extended to non-zero baryon chemical potential. The associated spectral
function has also been tested against the Euclidean correlator, for
continuum-extrapolated lattice data (at $\mu_{\rm B}=0$).
