\begin{table}%t5
\caption{Spectral index values and $V$ values for all spectra plotted in
 Fig.~\ref{spettri_storici}.}\label{indici_spettrali_V}
%\centering\small
\begin{tabular}{ccc}
\hline
\hline
{Data set} & {$\alpha$} & $V$ (mJy) \\
\hline
This work (13/5/2005) & 0.77 $\pm$ 0.16 & 16.485 $\pm$ 0.263 \\
This work (19/9/2005) & 0.88 $\pm$ 0.05 & 24.370 $\pm$ 0.238 \\
This work (4/11/2005) & 1.32 $\pm$ 0.24 & 35.278 $\pm$ 0.498 \\
Bertone at al. (2000) & 0.42 $\pm$ 0.26 & 26.20 $\pm$ 0.58 \\
Pesce et al. (1997) & 0.62 $\pm$ 0.30 & 24.50 $\pm$ 0.67  \\
Zhang \& Xie (1996) & 0.62 $\pm$ 0.16 & 22.90 $\pm$ 0.63 \\
Bersanelli et al. (1992) & 0.61 $\pm$ 0.38 & 51.88 $\pm$ 1.56 ($J$ band) \\
Treves et al. (1989) (1/12/1983) & 0.51 $\pm$ 0.31 & 19.80 $\pm$ 0.36 \\
Treves et al. (1989) (11/11/1984) & 0.51 $\pm$ 0.41 & 26.20 $\pm$ 0.48 \\
Miller \& McAlister (1983) & 0.62 $\pm$ 0.56 & 17.8 \\
\hline
\end{tabular}
\end{table}