Same as in Fig. 6 for the narrowest bandpass (region [I]). Near to the line center, the cross section is the highest, therefore probing the highest altitudes. The ground-based measurements obtained by Snellen et al. (2008) are plotted with crossed squares together with the spectroscopic evaluations (diamonds) of Sing et al. (2008a). The variations of the absorption depth (AD) between 1.5 and 3 Å bandpass are consistent with a temperature from 1500 to 4000 K with the most plausible value on the order of 2500 K.