Example of the two fitting methods developed in two previous studies (Kaplan et al. 2020; Ferrone et al. 2021): (a) linear least-squares fitting of normalized data and (b) a Kolmogorov-Smirnov fitting method, in which we search for the maximum distance between the two curves. The black curves are laboratory data with noise added to simulate OVIRS noise, and the red curves are laboratory data at their original S/N. Vertical lines at 3.10, 3.275, 3.38, 3.42, and 3.50 μm indicate positions of possible absorption features.