median energy is an important discriminant for distinguishing some contaminant populations. It can be effective for foreground stars and extragalactic sources, but not background stars which have the same median energies as many Carina PMS stars.

*J*-band Magnitude \[jmag\_contamination\_subsection\]
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Younger PMS stars with protoplanetary disks (infrared Class 0-I-II systems) can be readily distinguished from Galactic field stars by their infrared excess. But often, as in the Carina complex, the majority of stars associated with a star forming region are older, diskless (Class III) systems. X-ray studies are particularly effective in detecting Class III stars which have high levels of magnetic activity. While in some X-ray studies of star forming regions, IR color-color and/or color-magnitude diagrams can be employed to successfully distinguish between [*diskless*]{} PMS and older stars [e.g. @Getman05; @Getman06; @Kuhn10], the small source extinction range (typically only $A_V \sim 1-3$ mag for most parts of the Carina region) and the large range of distances (only with respect to color-magnitude diagrams) for the simulated contaminating stars (§\[contaminants\_stellar\_section\]) blunt this technique. Therefore, here we restrict our consideration to a simple near-IR photometric property, $J$-band magnitude. In addition to $J$-band magnitude, @Broos11b employ some near-IR and mid-IR colors to distinguish between 