  We discuss observations of the weak first overtone CO absorption band near
2300 nm with the U.S. National Solar Observatory Array Camera (NAC), a modern
mid-infrared detector. This molecular band provides a thermal diagnostic that
forms lower in the atmosphere than the stronger fundamental band near 4600 nm.
The observed center-to-limb increase in CO line width qualitatively agrees with
the proposed higher temperature shocks or faster plasma motions higher in the
COmosphere. The spatial extent of chromospheric shock waves is currently at or
below the diffraction limit of the available C0 lines at existing telescopes.
Five minute period oscillations in line strength and measured Doppler shifts
are consistent with the p-mode excitation of the photospheric gas. We also show
recent efforts at direct imaging at 4600 nm. We stress that future
large-aperture solar telescopes must be teamed with improved, dynamic
mid-infrared instruments, like the NAC, to capitalize on the features that
motivate such facilities.
