Temperature determination of the B star from ionisation equilibrium. The different panels are for different line combinations used to measure equivalent width ratios of Si III over Si II lines and Fe III over Fe II lines. The black line and shaded regions indicate the mean and uncertainties of the observed values. The coloured dots show the predicted ratios for the models of different logg as a function of T_eff. For an estimated value of logg between ≈2.0 and 2.5, the best-fit T_eff lies between 13000 and 14000 K, respectively.