\begin{table}%t3
%\centering
\par
\caption{\label{colors}Color indices of asteroid 21 Lutetia.}
%\tabcolsep1pt
\begin{tabular}{ccccc}
%\noalign{\smallskip\smallskip}
\hline
\hline
%\noalign{\smallskip}
Filters & ($U-B$) & ($B-V$) & ($V-R$) & ($R-I$)\\
\hline
$(F16-F24)$ & 0.22~$\pm$~0.02 & 0.68~$\pm$~0.02 & & \\
\\
$(F16-F23)$ & 0.21~$\pm$~0.02 & 0.67~$\pm$~0.02 & & \\
\\
$(F24-F23)$ & & 0.68~$\pm$~0.02 & & \\
\\
$(F24-F22)$ & & & 0.38~$\pm$~0.02 & \\
\\
$(F24-F28)$ & & & 0.38~$\pm$~0.02 & \\
\\
$(F23-F22)$ & & & 0.39~$\pm$~0.02 & \\
\\
$(F23-F28)$ & & & 0.39~$\pm$~0.02 & \\
\\
$(F22-F28)$ & & & & 0.32~$\pm$~0.02 \\
\\
$(F22-F51)$ & & & & 0.31~$\pm$~0.02 \\
\\
$(F22-F41)$ & & & & 0.32~$\pm$~0.02 \\
\hline
%\noalign{\smallskip}
Mean values & 0.22~$\pm$~0.01 & 0.68~$\pm$~0.01 & 0.39~$\pm$~0.01 & 0.32~$\pm$~0.01\\
\par
\\
Sun & 0.19 & 0.65 & 0.35 & 0.28\\
\hline
%\noalign{\smallskip}
PDS & 0.19~$\pm$~0.02	&	0.69~$\pm$~0.03 & & \\
Z+75 & 0.19~$\pm$~0.03 &	0.72~$\pm$~0.01 & & \\
L+83 &               & 0.67~$\pm$~0.02 & & \\
\\
D+00 &               & 0.68~$\pm$~0.02 & & \\
B+10 &  & 0.65~$\pm$~0.01 &	0.42~$\pm$~0.01 &  0.34~$\pm$~0.01\\
\hline
\end{tabular}
\tablefoot{The first block of data gives the individual color indices calculated from the various combinations of NAC filters used to derive the $UBVRI$ magnitudes.
The second block gives the corresponding mean values of the indices and those of the Sun for comparison.
The third block gives results found in the literature: PDS = Planetary Data System; Z+75 = Zellner et~al. (\cite{Zellner75}); 
L+83 = Lupishko et~al. (\cite{Lupishko83}); D+00 = Denchev (\cite{Denchev00}); B+10 = Belskaya et~al. (\cite{Belskaya10}).}
\end{table}