\begin{table}%t2
  \caption{Shape  parameters  for   the  main  and  secondary  lensing galaxies.}\label{gal_HST}
\par
  %\centering
\small
  \begin{tabular}{c|cccc}
    \hline
    \hline
    Obj.  & PA   ($^{\circ}$)  & Ellipticity & $a_{0}$ (\arcsec) & $b_{0}$   (\arcsec) \\
    \hline
    G1 & 27.8 $\pm$ 4.3 & 0.18 $\pm$ 0.03 & 0.665 $\pm$ 0.036 & 0.556 $\pm$ 0.025\\
    G2 &  6.4 $\pm$ 3.1 & 0.15 $\pm$ 0.02 & 0.389 $\pm$ 0.004 & 0.334 $\pm$ 0.005\\
    \hline
  \end{tabular}
\end{table}