The coronal properties of an exceptionally luminous quasar at z=0.821

High luminosity quasars are unique laboratories to test our understanding ofXray coronae in AGN. We propose joint XMMNewton and NuSTAR observations of aluminous, opticallyselected, nonjetted quasar at z0.821. Our main goal is tomeasure the highenergy cutoff in its Xray spectrum, hence constraining, in theframework of Comptonization models, its coronal temperature and optical depth. This will allow us to test whether the same physical conditions hold in quasarsat luminosities and masses 100 times higher than those probed in so far in thenearby Universe, exploring the unknown Xray properties of the quasar populationat intermediate redshifts (z 0.11), constituting half the age of theUniverse. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]