Nuclear modification factor $R_{pA}$ of isolated prompt photon production in p--Pb collisions at 8.16  TeV. The pp reference is obtained through extrapolation from 8 TeV to 8.16 TeV, which was obtained using the JETPHOX program at NLO and included the rapidity boost. The measurement is compared to an existing ATLAS measurement, where the reference is given in the legend. This figure is a derived figure and is plotted as log-x to show the full reach of the ATLAS measurement.