FIG. 23.

Signal-to-noise ratios needed to detect the O₂ A band, 1.06 μm dimer feature, and the 1.27 μm feature for direct imaging reflected spectra. As resolving power decreases, the required SNR to detect each feature increases because the continuum level decreases, resulting in a lower overall signal in the absorption band. Furthermore, at the lowest resolutions, the absorption bands cannot be resolved. Thus, this decreases the measurable signal even more, leading to an increase in the required SNR.