Spectrum of Mars integrated over the Martian disk (thick black line), recorded with EXES on April 8, 2014 (Ls = 113°, normalized radiance). Red line: best-fit model of Mars multiplied by our inferred terrestrial atmospheric transmission function. Top: 1383.5−1390.1 cm^-1; bottom: 1386.2−1387.8 cm^-1. The radiance is zero at 1387.5 cm^-1, as expected from the opacity of the terrestrial atmosphere at this frequency.