Marginal detection of two emission features of H₂O at 36.6 and 38.8 cm^-1 (1097 and 1163 GHz, respectively). The best-fitting mole fractions are and at 0.5 mbar, for each respective line. The left panels show line to continuum ratios for models computed by scaling the photochemical profile of Moses et al. (2000b), with the resulting Δχ² for each model shown on the right. The dotted lines in the left panels show the conservative error envelope as defined in the main text, the black circles are the SPIRE data. The right hand panel shows the Δχ² for each model, with dotted horizontal lines showing the 1σ confidence limits on the results.