\begin{table}%t2
%\centering
\par
  \caption {\label{table:slope}Comparison of the visible spectral slope S (in \%/100 nm) as computed from linear
    regression using the same algorithm on published data and our work over the common spectral range (0.51--0.76~$\mu$m).}    
%\centering
\par
%\renewcommand{\footnoterule}{}
\begin{tabular}{l l c c l  c} 
\hline\hline \noalign{\smallskip}      
Data reference      & UT date  &$r$(AU)\tablefootmark{a} & $\alpha (^{\circ})$\tablefootmark{b} &Instrument & Computed S (\%/100~nm)\\
\hline                    
This paper          &2005-04-09 &47.67 & 0.99 &Keck + LRIS-RB  & $2.01\pm0.54$\\
\cite{Fornasier+09} &2008-02-04 &47.81 & 0.48 &VLT + FORS2     & $1.75\pm0.57$\\
\cite{deBergh+05}   &2004-04-11 &47.62  &1.02  &VLT + FORS2     & $1.42\pm0.74$\\
\cite{Fornasier+04} &2004-02-29 &47.61  &0.46  &TNG + DOLORES   & $1.80\pm0.67$\\
\hline                  
\end{tabular}
\tablefoot{
\tablefoottext{a}{Heliocentric distance from JPL Horizons ephemeris.}
\tablefoottext{b}{Phase angle ($^\circ$) from JPL Horizons ephemeris.}}
\vspace*{-4mm}
\end{table}