I will describe how to gauge-invariantly quantize the degrees of freedom on a null ray segment in perturbative Einstein gravity. This will proceed in three steps: 1) the use of a `dressing time’ reference frame (formed out of the geometric area element and its conjugate partner) to gauge-invariantly localize the segment, 2) the quantization of the fields on the segment using a background-independent notion of covariant normal ordering (which can be understood as promoting the dressing time to a *quantum* reference frame), and 3) the cancellation of quantum diffeomorphism anomalies by a deformation of the classical phase space.