Umbriel grand average spectra (black, A–D) and 1σ uncertainties (light gray error bars) compared to a grand average spectrum and 1σ uncertainties (light gray error bars) of Ariel (black, E). The grand average Ariel spectrum was generate using the five IRTF/SpeX spectra that display >3σ band area and depth measurements for Ariel’s 2.2 μm band (reported in Cartwright et al. 2020c). All five spectra are normalized to unity between 1.74 and 1.77 μm and offset vertically for clarity. Each spectrum has been smoothed using a 10–14 pixel wide boxcar function, whereas the 1σ uncertainties are shown at their native resolutions. The range in band centers for Umbriel’s 2.14 μm, 2.2 μm, 2.22 μm, and 2.24 μm bands (Tables A2–A5) is highlighted by the purple, blue, green, and red zones, respectively.