\begin{table} %T3
%\centering
\small
\caption{Setups for the optical spectroscopy.}\label{tab:wave} 
\begin{tabular}{rcc}\hline\hline 
 & FORS1 & FORS2 \\\hline 
Grism & GRIS\_150I+17 & GRIS\_150I+27\\ 
Dispersion [$\AA /$mm]& 230&225 \\ 
Pixel size [$\mu$m]& 24 $\times$ 24& 15 $\times$ 15\\ 
Step width [$\AA/$Pixel]& 5 & 3 \\\hline 
\end{tabular} 
\end{table}