Spatial distribution of the SVS13-A region obtained using the OCS(7–6) (upper panel), OCS(8–7) (middle), and OCS(17–16) (bottom) line emission (contours and colour). The whole velocity emitting region has been used (from 0 km s⁻¹ to +20 km s⁻¹, see Fig. 9). Angular offsets are shown relative to the phase centre (see Sect. 3). First contour and steps are 5σ and 10σ, respectively. The 1σ value is 5 mJy km s⁻¹ (J = 7–6, and 8–7), and 26 mJy km s⁻¹ (J = 17–16). The filled ellipse shows the synthesized beam (HPBW): 1.′′6 × 1.′′1 (PA = 41°) for OCS(7–6) and OCS(8–7) and 0.′′65 × 0.′′58 (PA = –46°) for OCS(17–16). The black crosses indicate the positions of the VLA4A and VLA4B sources as imaged using the VLA array by Tobin et al. (2018).