Fig. 2: WASP-39b transmission spectra measured at 10-pixel resolution (≈7-nm-wide bins, R ≈ 600) using several fitting pipelines.

We show the resultant spectra from five out of 11 independent fitting pipelines, which used distinct analysis methods to demonstrate the robust structure of the spectrum (see Methods for details on each fitting pipeline and comparative statistics). The black points show the weighted-average transmission spectrum computed from the transit depth values in each bin weighted by 1/σ², in which σ is the uncertainty on the data point from each of the 11 fitting pipelines. The error bars were computed from the unweighted mean uncertainty in each bin (see Extended Data Fig. 5). All spectra show consistent broadband absorption short of 3.7 μm, around 4.1 μm and from 4.2 to 4.5 μm.