Geometry of the Mars observations taken by SOFIA/EXES. The instrument slit was oriented at a position angle of 260^∘ . The slit is indicated as white boxes, and were put at the three separate slit positions: “Mars Center”, “Mars Right 2.5”, and “Mars Left 2.5”. For the center position, the slit was placed over the sub-Earth point. For the right and left positions, we offset the center of the slit to 2.5′′ perpendicular to the slit angle. In this analysis, the measured spectra were binned over 15 pixels (~2.7′′) along the slit in order to increase the signal to noise ratio. As a consequence, three averaged spectra were obtained for each slit position.