essencially based in the color criteria of @Gutermuth:2008aa and @Kryukova:2012aa, but as explained by @Ybarra:2013aa we add an additional \[5.8\]-\[8.0\] criteria for objects that do not have a MIPS 24 $\mu m$ detection. In addition, our use of $JHK$ photometry allows us to identify additional less bright candidates and with the use of X-ray data we are able to identify Class III sources that do not have an infrared excess.

Class III candidate sources were selected from a list of sources in the Chandra catalog that match in position with an infrared point source, after removing those corresponding to Class I/0 and Class II candidates. We added the requirement that $$J-H\ge0$$, because sources with $J-H<0$ are most likely either galaxies or spurious sources associated with diffraction spikes of bright stars. We further depurated this first counterpart list by keeping only those sources that had no evidence of a prominent circumstellar disk (i.e., we only selected stars with mostly photospheric emission). For this last criteria we used the $J-H$ vs $K-[4.5]$ color space:

$$J-H>1.97(K-[4.5]).$$

and for those sources that do not have a detection in \[4.5\] we used:

$$J-H>1.74(H-K).$$

The remaining list of Chandra-NIR counterparts are sources with evidence of a 