POSEIDON atmospheric and stellar retrieval results for WASP-52b. Top: NIRSpec/G395H transmission spectrum from the transitspectroscopy data reduction, with the two models varying stellar parameters overplotted. The unocculted starspots introduce an upward spectral slope, indicated by the gray arrow. The NIRSpec/G395H NRS2 data are offset by the median retrieved offset from each model. Each model has a median retrieved spectrum (solid line) and the ±1σ confidence interval (shaded contours). Bottom: retrieval models’ posterior distributions with their median values (solid lines) and their ±1σ confidence intervals (dashed lines). The stellar contamination parameters are highlighted in the top row, and atmospheric parameters are highlighted in the middle and bottom rows (see Table 3 for full retrieval results).