Search for an Near-IR Counterpart to the Cas~A X-ray Point Source

e report deep near-infrared and optical observations of the X-ray point source in the Cassiopeia~A supernova remnant, \Src. We have identified a $J=21.4 \pm 0.3$~mag and $K_{s}=20.5 \pm 0.3$~mag source within the 1-$\sigma$ error circle, but we believe this source is a foreground Pop~II star with $T_{\rm eff}=2600$--2800~K at a distance of $\approx 2$~kpc, which could not be the X-ray point source. We do not detect any sources in this direction at the distance of Cas~A, and therefore place 3-$\sigma$ limits of $R \gsim 25$~mag, ${\rm F675W} \gsim 27.3$~mag, $J\gsim 22.5$~mag and $K_{s} \gsim 21.2$~mag (and roughly $H \gsim 20$~mag) on emission from the X-ray point source, corresponding to $M_{R} \gsim 8.2$~mag, $M_{\rm F675W} \gsim 10.7$~mag, $M_{J} \gsim 8.5$~mag, $M_{H} \gsim 6.5$~mag, and $M_{K_{s}} \gsim 8.0$~mag, assuming a distance of 3.4~kpc and an extinction $A_{V}=5$~mag.