Variation of the planetary radius, expressed as transit depth, as a function of wavelength. Sky-blue points correspond to Danish-DFOSC (this work), lime to TESS (this work), orange to GROND (Mancini et al. 2013), crimson to MMIRS (Bean et al. 2013), green to Sedaghati et al. (2015), and black to Huitson et al. (2013). Vertical error bars represent measurement uncertainties, while horizontal bars indicate the full width half maximum (FWHM) of the respective passbands. Synthetic photometric points were computed using the SVO SpecPhot tool to obtain flux-weighted transit depths at the effective wavelengths of the UV-optical filters. Retrievals were performed with POSEIDON including the opacities of Na, K, TiO, VO, and H₂O. The orange curve shows the median best-fit model excluding TiO and VO, with 1σ and 2σ confidence intervals. The purple curve shows the median best-fit model including TiO and VO, with corresponding uncertainties. See Sect. 6.2 for details.