H₂CO emission towards SVS13-A. Upper panel: spatial distribution of the o-H₂CO(6_1,5–6_1,6) emission. The whole velocity emitting region has been used (from –5 km s⁻¹ to +20 km s⁻¹). The angular offsets are relative to the phase centre (see Sect. 2). First contour and the respective steps are 5σ (25 mJy km s⁻¹) and 20σ, respectively. The filled ellipse shows the synthesized beam (HPBW): 1.′′6 × 1.′′1 (PA = 41°). The black crosses indicate the positions of the VLA4A and VLA4B sources as imaged using the VLA array by Tobin et al. (2018). Lower panel: observed o-H₂CO(6_1,5–6_1,6) spectrum (in T_B scale, see Table 1) extracted at the emission peak: α₂₀₀₀ = 03^h29^m03.^s75, δ₂₀₀₀ = +31°16′03.′′8. The upper level energy is reported. The vertical dashed line stands for the ambient LSR velocity (+8.6 km s⁻¹, Chen et al. 2009).