T_eff fit results from fitting the wings of the Balmer lines Hγ (left), Hβ (middle), and Hα (right). Upper panels: observed spectra (gray) with the best-fit 3D NLTE models (5260/5260/5360 K) by Amarsi et al. (2018) and their error margins of 100 K depicted by red lines and blue areas, respectively. The wavelength regions used to obtain the continuum level are marked in blue, whereas orange lines highlight the parts of the spectrum that entered the χ² minimization. Lower panels: residual spectrum.