Hα image of the region surrounding RS Oph, which is indicated by diagonal red ticks. The proper motion of RS Oph (with a Gaia-measured amplitude of 6.11 mas yr⁻¹) is shown as a white arrow, whose length corresponds to the motion of RS Oph in the past 50 kyr. The positions of two inner and one outer SALT RSS slits, described in Section 2, are shown as yellow, magenta, and cyan lines, respectively. The image has been smoothed via a Gaussian kernel (σ = 3 pixels) and is displayed with linear scaling. The direction of proper motion of RS Oph is approximately perpendicular to the linear feature marked by yellow brackets in Figure 1, suggesting that this feature might be material snow-plowed by RS Oph.