Orion dust opacity map at 850 µm by Lombardi et al. (2014), convolved at an angular resolution of 36″. Contours are (0.056, 0.24, 0.56, 1.36, and 1.61) × 10²¹ cm⁻², which, according to Lombardi et al. (2014), correspond to visual extinctions of ~1.3, 5.6, 13.2, 23.8, and 38 mag. Positions observed with the 30m telescope are indicated with white triangles. Red circles represent the positions of the starless cores. Labels in red indicate the cut IDs (see Table 1).