\begin{table}%t3 \caption{\label{Xray_results}Spectral information from X-ray observations of H~2356--309. } %\centering \par \begin{tabular}{lcccccccc} \hline\hline \noalign{\smallskip} Instrument & MJD & Model & $\Gamma_1$ & $E_{\rm break}$ & $ \Gamma_2$ &$F_{0.1-2.0~\rm keV}$ & $F_{2-10~\rm keV}$ & $\chi^2_{\rm r}$,~NDF\tablefootmark{a}\\ \noalign{\smallskip} & & & & [keV] & & \multicolumn{2}{c}{[$10^{-12}$ erg cm$^{-2}$ s$^{-1}$]\tablefootmark{b}} & \\ \noalign{\smallskip} \hline \noalign{\smallskip} BeppoSAX & 51~350--51 & BPL & $\rm 0.78^{+0.06}_{-0.07}$ & $1.8 \pm 0.4$ & $1.10 \pm 0.04$ & -- & 25 & --\\ RXTE & 53~320 & PL & $2.43 \pm 0.25$ & -- & -- & -- & $\rm 9.70^{+0.3}_ {-1.3}$ & --\\ \noalign{\smallskip} \hline \noalign{\smallskip} XMM-Newton\tablefootmark{c} & 53~534 & PL & $2.23 \pm 0.01$ & -- & -- & 25.9 & 8.05 & 1.41,~541\\ & & BPL & $2.08 \pm 0.03$ & $1.00 \pm 0.08$ & $2.32 \pm 0.02$ & 23.2 & 7.46 & 0.95,~539 \\ \noalign{\smallskip} XMM-Newton$^{c}$ & 53~536 & PL & $2.16 \pm 0.01$ & -- & -- & 25.9 & 9.54 & 1.52,~541\\ & & BPL & $1.89 \pm 0.10$ & $0.66 \pm 0.14$ & $2.20 \pm 0.02$ & 22.3 & 9.15 & 1.21,~539\\ %XMM confidence level 90% 1 param (deltachi=2.709) \noalign{\smallskip} \hline \end{tabular} \tablefoot{\tablefootmark{a}{The reduced $\chi^2_{\rm r}$ and degrees of freedom (NDF) correspond to fits of either a power-law (PL) function or broken power-law (BPL) function to the XMM-Newton X-ray data.} \tablefootmark{b}{The integrated fluxes have the effects of Galactic absorption removed.} \tablefootmark{c}{All errors from the XMM-Newton fits are quoted at the 90\% confidence level.}} \end{table}