\begin{table}%t2
\caption{Best-fit parameters of the models adopted to describe the 
X-ray spectrum of Swift J1656.3$-$3302.}\label{tab2}
%\centerline
{\small   \begin{tabular}{lr}
\hline
\hline
\multicolumn{1}{c}{Parameter} & \multicolumn{1}{c}{Value} \\
\hline
\multicolumn{2}{c}{power law plus Galactic absorption} \\
%\hline
$\chi^2$/d.o.f.       & 45.6/34 \\
$\Gamma$         & $1.28 \pm 0.10$ \\
XRT/IBIS intercalibr. constant    & $0.7 ^{+0.4}_{-0.2}$ \\
$F_{\rm (2-10~keV)}$       & $4.9 \times 10 ^{-12}$ \\
$F_{\rm (20-100~keV)}$  & $1.9 \times 10 ^{-11}$ \\
\hline
\multicolumn{2}{c}{power law plus Galactic and intrinsic absorption} \\
\noalign{\smallskip}
$\chi^2$/d.o.f. & 25.2/33 \\
$N_{\rm H}$ (10$^{22}$~cm$^{-2}$) & $\rm 6.7^{+3.2}_{-2.7}$ \\
$\Gamma$ & $1.64\pm 0.16$ \\
XRT/IBIS intercalibr. constant & $\rm 1.9^{+1.3}_{-0.7}$ \\
$F_{\rm (2-10 ~keV)}$    & $4.6\times10^{-12}$ \\
$F_{\rm (20-100 ~keV)}$  & $2.2\times10^{-11}$ \\
\hline
\multicolumn{2}{c}{broken power law plus Galactic absorption} \\
$\chi^2$/d.o.f. & 23.6/32 \\
$\Gamma_1$ & $\rm 0.86^{+0.23}_{-0.26}$ \\
$\Gamma_2$ & $\rm 1.81^{+0.23}_{-0.13}$ \\
$E_{\rm break}$ (keV) & $\rm 2.7^{+1.5}_{-0.5}$ \\
XRT/IBIS intercalibr. constant & $\rm 2.9^{+1.5}_{-1.3}$ \\
$F_{\rm (2-10~keV)}$    & $4.4 \times 10^{-12}$ \\
$F_{\rm (20-100~keV)}$  & $2.0 \times 10^{-11}$ \\
\hline
\end{tabular}}
\smallskip
{Note: In the above fits, when needed, we fixed the redshift} 
{of the source at $z=2.40$ and the Galactic hydrogen column} 
{at $N_{\rm H}^{\rm Gal} = 2.2 \times 10 ^{21}$~cm$^{-2}$.} 
{The reported fluxes (in the observer's frame) are in erg}~{cm$^{-2}$~s$^{-1}$ and are corrected for the total intervening} 
{absorption column density.} 
{For the broken power law model, the fit parameters} 
{are computed in the observer's frame, and not in the} 
{source rest frame.} 
\end{table}