Transmission and emission spectra for all stable atmospheres found for T-1 c (without trace SO₂). The top three rows (white background) and bottom three rows (gray background) show atmospheres sourced from H₂O and H₂O–CO₂ outgassing, respectively. Each row corresponds to a different atmospheric archetype (described in text), from top to bottom: H₂O dominated; O₂ dominated (produced via H₂O outgassing); mixed H₂O₂; mixed CO₂–CO; O₂ dominated (produced via H₂O–CO₂ outgassing); and mixed O₂–H₂O–CO₂. The left column shows visible to near-infrared transmission spectra (0.001–6.5 μm); the middle column shows secondary eclipse emission spectra at thermal wavelengths (8–17 μm); and the right column shows nightside thermal emission at 15 μm. The transmission spectra are colored by their fit (σ deviation) to available T-1 c transmission data (M. Radica et al. 2025), and the emission data are colored by their combined fit to all available emission data (15 μm day and night points; S. Zieba et al. 2023; M. Gillon et al. 2026). Spectral features are labeled with the absorbing gas. The overall best-fitting atmospheres for T-1 c include lower-pressure (<0.2 bar), O₂-dominated atmospheres (regardless of outgassing source) and mixed O₂–H₂O atmospheres.