Attenuation factor for a photon with energy E_γ produced at position z in the jet due to annihilation with the intrajet and external radiation fields (the same in both models). The left panel shows the contributions to the opacity of the disk radiation field at low z and, for Model B, that of the intrajet synchrotron field at high z. The latter is negligible in Model A. The right panel shows the same for the stellar radiation field.