Spatial distribution of stars from four different surveys. From upper to lower panels: optical catalog (V and I_C bands) from Hillenbrand (1997), IR catalog (H and K bands) from Hillenbrand Carpenter (2000), IR catalog (J, H and K_S bands) from Muench et al. (2002), and IR catalog (L′ band) from Lada et al. (2004). As in Fig. 1, dashed contours represent dense gas traced by the integrated intensity emission of CN (N = 1–0) (Rodríguez-Franco et al. 1998). The left panels show the position of the X-ray stars as blue dots. Four crosses, an open square and an open triangle show the location of the four main-sequence massive Trapezium stars, the OHC, and OMC1-S. The right panels report the stellar surface density for the same extinction ranges, derived by counting the number of COUP sources using a kernel box of 15′′ (0.03 pc) (right color scale), superimposed on the CN emission.