\begin{table}%t3 \caption{\label{table:ss1_spec}Comparison of SS1 spectral best fit parameters and derived parameters for blackbody and WD atmosphere models with halo and solar abundances.} \small %\centerline { \begin{tabular}{lrrr} \hline \hline\noalign{\smallskip} Model & Blackbody & WD halo & WD solar\\ (energy range [keV]) & (0.2--0.8) & (0.2--0.6) & (0.2--0.6)\\ \noalign{\smallskip}\hline\noalign{\smallskip} kT (eV) & $48^{+2}_{-3}$ & $61\pm1$ & $70\pm1$\\ \noalign{\smallskip} \nh ($10^{21}$ cm$^{-2}$) & $2.3\pm0.1$ & $1.0\pm0.2$ & $1.0\pm0.2$\\ \noalign{\smallskip} $\chi^{2}_{r}$ & 1.39 & 1.01 & 1.06\\ \noalign{\smallskip} d.o.f. & 53 & 44 & 48\\ \noalign{\smallskip} \hline \noalign{\smallskip} $L_{x}$ ($10^{38}$ \hbox{erg s$^{-1}$}) & $10.6 \pm 0.2$ & $1.00 \pm 0.02$ & $0.88 \pm 0.02 $\\ \noalign{\smallskip} $L_{bol}$ ($10^{38}$ \hbox{erg s$^{-1}$}) & $\rm 28.7^{+0.2}_{-0.1}$ & $2.7 \pm 0.1$ & $1.5 \pm 0.1$\\ \noalign{\smallskip} $R$ (\power{9} cm) & $\rm 7.0^{+1.6}_{-0.7}$ & $1.21 \pm 0.07$ & $0.70 \pm 0.04$\\ \noalign{\smallskip} ecf$_{\rm PN}$ (ct cm$^2$ erg$^{-1}$) & 5.0~\tpower{9} & 5.5~\tpower{10} & 6.1~\tpower{10}\\ \noalign{\smallskip} ecf$_{\rm HRC{-}I}$ (ct cm$^2$ erg$^{-1}$) & 2.6~\tpower{9} & 3.2~\tpower{10} & 3.7~\tpower{10}\\ \noalign{\smallskip} ecf$_{\rm XRT}$ (ct cm$^2$ erg$^{-1}$) & 7.4~\tpower{8} & 8.7~\tpower{9} & 9.9~\tpower{9}\\ \hline \end{tabular}} \par \medskip Notes:\hspace{0.3cm} Luminosities and WD radii refer to the \xmm observation 0511380201. The unabsorbed X-ray luminosity $L_{x}$ is for the 0.2--1.0 keV range. Bolometric luminosities and WD radii for the WD atmosphere model are upper limits (see Sect.~\ref{sect:sss_bol111} for details). %\hspace*{1.5cm} \end{table}