New SEPIA660 observations along the OMC-1 region. From left to right: (a) VISTA-IR K_s band (Meingast et al. 2016); (b) APEX-SEPIA660 N₂H⁺ (7–6); and (c) APEX-SEPIA660 C¹⁸O (6–5) maps(this work). All molecular maps are convolved into a common Nyquist grid with a final resolution of 10″. The intensity the H41α emission tracing the extension of the ONC HII nebula (red contours, Hacar et al. 2020) is indicated in the VISTA image. Panels b and c: equally spaced contours (black) every W(N₂ H⁺(7−6)) = 2.5 K km s⁻¹ and W(C¹⁸O (6−5)) = 10 K km s⁻¹, respectively. For reference, the position of the Trapezium (white stars) and the Orion BN source (yellow star), as well as the first contour of the N₂H⁺ (1–0) emission (W(N₂H⁺(1−0)) = 1.0 K km s⁻¹, white contour), are displayed in all panels (Hacar et al. 2018, see also Fig. 2a).