Left panel: spatial density of the foreground sources (blue sample). The unshaded area in the figure represents the region of the cloud where A_V ≥ 5 mag, on which the selection was performed. The blue contours (with increments of 10% from the maximum) represent the surface density of foreground sources (constructed with a Gaussian kernel with a width of 20′). Right panel: same as in the left panel but for the reddened sources. The distribution of foreground sources shows a clearly defined peak coinciding with the poorly studied NGC 1980. The reddened sources, on the other hand, peak around 1) the Trapezium cluster and are mostly confined to the nebula and 2) the L1641N star-forming region, with a peak toward a hitherto unrecognized group of YSOs (see text). The reddened and foreground populations are spatially uncorrelated but there is significant overlap between the two, in particular with the sources inside the Orion nebula.