Best-fit central velocity for the Gaussian fit to H₂CO 3_0,3–2_0,2, for emission with S/N> 5. Black contours mark 5, 10, 15 and 20 times the rms level (0.8 K km s⁻¹) of the SO₂ 11_1,11–10_0,10 integrated intensity image from Fig. 1. The black curve represents the streamer trajectory from Valdivia-Mena et al. (2022). An ellipse in the bottom-left corner represents the beam. The scale bar in the top right shows a length of 200 au.