Upper panel: distribution of the C¹⁷O(3–2) centroid positions (from fits in the uv domain with 1σ error bars) in the various velocity channels (Fig. A.1). Red and blue datapoints denote the channels whose fitted centroids lie, within the error bars, on the equator. Bottom panel: velocity shift from V_sys as a function of distance from the protostar along the equator (PA = 122°). Red and blue datapoints denote the channels whose fitted centroids lie along the equator (see upper panel). The assumed systemic velocity is +1.3 km s^-1 (see text). Grey points refer to LV emission tracing the C¹⁷O envelope and cavity. Black solid and dotted curves show Keplerian rotation around a stellar mass of 0.3 ± 0.1 M_⊙. The r^-1 curve for angular momentum conservation is plotted in magenta for comparison.