GTC/OSIRIS optical spectrum of W1738, co-added with the spectrum by Leggett et al. (2016) in the range 10 000–10 900 Å, compared with theoretical 1D-slab far-red optical and near-infrared spectrum of H₂S calculated for a temperature of 450 K and a resolving power of 200. Several absorption features of H₂S can be seen that could correspond to those observed and are still unidentified in the W1738 spectrum.