Analysis of the shape of the reflectance spectra at 111° ± 25°W, 38° ± 16°S at wavelengths of 1.100–1.300 μm. (a) Close-up view of the reflectance spectra fitted by the calculated H₂O-ice spectra. (b) Normalized spectra of hydrated Cl-bearing salts compared with differences between the observed and fitted H₂O-ice spectra as a function of wavelength. Reflectance spectra of H₂O ice are calculated using the Hapke model (Hapke 1981, 1993, 2002) with the optical constants for amorphous H₂O ice at 70–130 K (Mastrapa et al. 2008), crystalline H₂O ice at 120 K (Grundy & Schmidt 1998), and H₂SO₄ · 8H₂O at 77 K (Carlson et al. 2005). The optical constants of H₂O ice are supplemented with optical constants from Warren & Brandt (2008). The reflectance of H₂O ice is fitted to the observed reflectance using the least-squares method at wavelengths of 1.100–1.130 μm and 1.255–1.300 μm. In the best fit with crystalline H₂O ice plus H₂SO₄ · 8H₂O, the mixing ratios of H₂O ice and H₂SO₄ · 8H₂O are calculated as 54% and 46%, respectively. Offsets have been added to the differences and the normalized spectra for clarification. The gray bar represents the wavelengths corresponding to telluric atmospheric absorption (1.13–1.15 μm). The normalized spectra of hydrated Cl-bearing salts are not scaled to their upper limits to the abundances.