Full retrieval model fit to the WASP-117b transmission spectrum in HST/WFC3 and VLT/ESPRESSO with the nominal pipeline with Na and K. The WFC3 data are shown in the top panel, the middle panel shows the Na doublet, and the bottom panel the K D₁ line. The retrieval model without Na and K (not shown) is a flat line in the optical and is indistinguishable from the full model without Na and K in the WFC3 near-infrared range. For all spectra, retrieved atmosphere models with confidence within 1σ (dark green) and 2σ (light green)are shown.