Interstellar polarization of the field stars around RS Oph (Heiles 2000; Cropper 1990). The degree of polarization is proportional to the length of the orange straight lines. The horizontal bar at the top left presents 4.0% polarization. The PA of the stars in the direction of RS Oph (with blue bar) is similar to that of RS Oph during quiescence (red line; Nikolov et al. 2019). The color of every star corresponds to its distance. The background image represents 100 μm dust emission maps (Schlegel et al. 1998).