Simulated spectra (re-binned to R=100) for the atmospheres of a HD189733b-like planet observed with NIRISS SOSS and NIRSpec G395M (left column) and with NIRCam F322W2 and MIRI LRS (right column). The VMR was set to 10⁻⁶ for the hydrocarbon molecule specified in each legend for the simulated observed spectra. The best-fit retrieved spectra are given in orange for the cases where the molecule was removed, and in purple when it was included in the retrieval. The shading of the best-fit spectra corresponds to 1, 2, and 3 σ regions.