surface densities of the X-ray contaminants detected in the ONC and Cep B observations (§ \[sec\_introduction\]) are 0.8 and 0.2 source arcmin$^{-2}$, respectively. A variation among these numbers is a product of multiple competing factors such as, detection technique, exposure times, thicknesses of molecular clouds and distances to the clouds, Galactic coordinates.

Across most of the Carina molecular cloud, the absorption is low, typically $A_V < 3$ mag, and reaches $\sim$10 mag only in a few small molecular cores [@Yonekura05]. Thus the spatial distributions of the simulated contaminants for all classes of the contaminants are relatively uniform across the field of view. We ignore small differences in the surface density of field stars between the northern (closer to the Galactic plane) and the southern portions of the CCCP field, predicted by the Besançon model: $<2$% and $<5$% for the foreground and background stars, respectively. The spatial distribution of the contaminants is very different from the clustered distribution of the observed CCCP sources, as shown in maps of the source distributions [@Townsley11a; @Feigelson11]. The difference can be quantitatively seen in projection along the right ascension axis (Figure \[fig\_spatial\]). The lower numbers of simulated contaminating sources at the both ends of the 