Normalized θ (5040/T_eff) as a function of the pulsation phase. The panels show the phase-folded curves separating the Cepheids in different bins of pulsation period (values within parentheses): from 3 to 5 days, from 5 to 7 days, from 7 to 9.5 days, and from 9.5 to 10.5 days. For the variable S Sge, the two outliers shown in Fig. B.2 were not used in the construction of the T_eff curve templates. The curves display the fit of the Fourier series to the data (see Table 7). The standard deviations of the fit are also shown.