Position-velocity diagram (v_LSR vs l) for APOGEE-2 observed sources in the southern Orion region. The 14 subregions are shown as colored circles (see legend and Fig. 1), with the error bars representing the velocity dispersion (Table 3). The red circle indicates the average position and velocity of Orion X in this PV-space (error bar smaller than the symbol size), with the red horizontal bar showing the projected l-extent of the scatter of known group members (Chen et al. 2020). The box-symbols represent the predicted PV-position of each corresponding cloud, if they were following the Galactic rotation curve without perturbation. The blue shaded area is shown as reference and encloses predicted motions for objects that are located between 200 pc < d < 600 pc, 215° > l > 198.5°, and −27° < b < −11°. For orientation we labeled the head and tail of Orion A, as well as other well-known stellar groups visible as over-densities in the PV-scatter (see Sect. 5.3). The distribution of v_LSR motions is presented in the histogram on the right, which is bimodal with one peak centered at about 5 km s⁻¹ and another between 10 and 15 km s⁻¹. The latter is dominated by the ONC and other young stellar groups. The gap in the middle (l ∼ 207.5) is largely caused by data incompleteness in APOGEE-2, in combination with a lack of stellar clusterings in this region.