Azimuthal distribution of the R band disk polarization, Q_ϕ(ϕ), of RX J1604 for normalized data, which is equivalent to a correction of an interstellar polarization of p_*(R) = 0.35% and θ_*(R) = 124° (black), and for data corrected for an interstellar polarization of (Q/I)_is(R) = 0.03% and (U/I)_is(R) = −0.22% to roughly match the shadow position in the near IR (blue). In both cases, the polarization was also corrected for the telescope polarization, p_t+i, which on its own would produce the profile shown in red.