Simulated emission spectra of the dayside as observed with JWST/NIRISS SOSS, using Pandexo (Batalha et al. 2017). Solid lines: high-resolution models assuming a temperature inversion up to 3200 K (see Fig. 2) at a metallicity of 5 times solar (solid lines). Transparent dots: Pandexo simulation at the native instrument resolution. Solid dots: Binned to a resolving power of 100. Purple: model with Ti and TiO. Orange: model without Ti and TiO. If TiO is indeed absent from the dayside emission spectrum of WASP-121 b, TiO bands will be strongly ruled out at the shortest wavelengths of NIRISS, while the VO band strength near 1 μm will be hard to discern. We note that the water band at 1.4 μm is barely visible by eye due to the scale of the axes, but the increased contrast from 1000 to 1500 ppm between 1.3 and 1.6 μm is consistent with the WFC3 data (see Fig. 2 of Evans et al. 2017).