Thick black line: TEXES spectrum of Mars in the vicinity of the HDO line at 1236.295 cm^-1 (July 3, 2014; Ls = 156°), integrated over 9 pixels in region B, compared with synthetic spectra. The continuum fluctuation in the TEXES data has been corrected by using the continuum on each side of each line and assuming a straight line between these two points. The airmass is 1.55. Models: H₂O = 300 ppbv (green), 375 ppbv (red), 450 ppbv (blue). The best fit is obtained for H₂O = 375 ppbv.