\begin{table}%T7 \par \caption{\label{tab:sun}The colours of the Sun.} \small%\centering \par \begin{tabular}{ccccc} \hline\hline\noalign{\smallskip} & $\teff$ scale & MARCS & ATLAS9 & Twins \\ & $({\rm rand.} + {\rm syst.\;errors})$ & & & \\ \hline $B-V$ & $0.641\pm 0.024 \pm 0.004$ & 0.622 & 0.645 & \\ $V-R_{\rm C}$ & $0.359\pm 0.010 \pm 0.003$ & 0.357 & 0.358 & \\ $(R-I)_{\rm C}$ & $0.333\pm 0.010 \pm 0.002$ & 0.347 & 0.349 & \\ $V-I_{\rm C}$ & $0.690\pm 0.016 \pm 0.004$ & 0.704 & 0.707 & \\ $V-J$ & $1.180\pm 0.021 \pm 0.007$ & 1.171 & 1.180 & \\ $V-H$ & $1.460\pm 0.023 \pm 0.010$ & 1.458 & 1.479 & \\ $V-K_{\rm S}$ & $1.544\pm 0.018 \pm 0.010$ & 1.543 & 1.553 & \\ $J-K_{\rm S}$ & $0.362\pm 0.029 \pm 0.003$ & 0.372 & 0.373 & \\ $(B-V)_{\rm T}$ & $0.730\pm 0.031 \pm 0.006$ & 0.723 & 0.750 & $0.735 \pm 0.024$\tablefootmark{a}\\ $V_{\rm T}-J$ & $1.254\pm 0.022 \pm 0.008$ & 1.240 & 1.250 & $1.254 \pm 0.041$\tablefootmark{a} \\ $V_{\rm T}-H$ & $1.534\pm 0.019 \pm 0.011$ & 1.527 & 1.550 & $1.549 \pm 0.048$\tablefootmark{a} \\ $V_{\rm T}-K_{\rm S}$ & $1.619\pm 0.013 \pm 0.011$ & 1.612 & 1.623 & $1.623 \pm 0.040$\tablefootmark{a} \\ $b-y$ & $0.409\pm 0.010 \pm 0.002$ & & & $0.409 \pm 0.003$\tablefootmark{b} \\ \hline \end{tabular} \tablefoot{For the indices obtained inverting our $\teff$ scale, random errors are from the dispersion of the fits in Table~\ref{tab:ct}. The uncertainty on the zero point of our $\teff$ scale is of order $15$~K (Sect.~\ref{tuning}), which usually implies systematic errors considerably smaller than the random ones. The only exception is for optical-infrared indices which are very sensitive to $\teff$ and show small intrinsic scatter, of the order of the aforementioned zero point uncertainty. Also shown for comparison are the averaged colours and standard deviation of the solar twins, as well as the synthetic colours computed from the ATLAS9 \citep{castelli04} and MARCS \citep{gustafsson08} models.\\ \tablefoottext{a}{Average and standard deviation of the colours in Table~\ref{t:twins}.}\\ \tablefoottext{b}{From Mel{\'e}ndez et al.~in prep., fitting solar twin colours as a function of $\teff$, $\feh$ and log $g$.}} \end{table}