\begin{table}%t1
\caption{\label{tab:pnvsmos}Main observational parameters for the nine \XMM\
datasets using for the uncertainties a 1$\sigma$ confidence level.}
%\centerline
 {\small \begin{tabular}{cccccccc}
\hline \hline\noalign{\smallskip}
Epoch & Period & Instrum. (mode)  & Exp.~Time  &  tot ph-bck ph   &
$\tau_{\rm max}$ edge& Energy edge & $\chi^2_{\rm red}$\\
  & s    &   &  s   &  & & keV & \\
\hline 
Sep. 2003 &5.53928(3)    &EPN   &5199 & 60~136--2903 & $<$0.17& 1.10(fix)&$^a$\\
& &MOS1 & 7700  & 30~761--111  & $<$0.02& 1.10 (fix)& 1.33\\
& &MOS2 & 7800 &  26~739--145  & $<$0.03&1.10 (fix)&\\
Mar. 2004 &5.53945(1)    &EPN  & 10~730 & 71~180--3077    & $<$0.18   &1.10 (fix)& \\
& &MOS1 & 12~000   & 27~932--396 & $<$0.03 &1.10(fix)& 1.15\\
& &MOS2 & 12~200   & 28~809--366  & $<$0.05&1.10(fix)&\\
Sep. 2004 &5.539599(6)   & EPN  & 21~306  & 89~082--1574    & $<$0.17 &1.10(fix)&  \\
&  &MOS1  & 24~000  & 35~515--263   & $<$0.06&1.10(fix)& 1.22\\
& &MOS2 & timing mode &  timing mode & timing mode & timing mode& timing mode\\
Mar. 2005 &5.539825(6)   &EPN  & 24~988  & 54~279--1760   & $0.12\pm0.03$&
$1.14\pm0.02$ & \\
 & &MOS1 & 37~800  & 26~501--428  & $0.09\pm0.04$& $1.10\pm0.03$ & 1.05   \\
 & &MOS2 & 37~800  & 28~004--330  & $0.10\pm0.02$& $0.98\pm0.08$ & $''$   \\
Sep. 2005 &5.54004(1)   & EPN & 19~787  & 21~876--1311   & $0.26\pm0.04$& $1.07\pm0.02$ &   \\ 
 & &MOS1 & 30~000  & 10~562--344    & $0.2\pm0.1$& $1.13\pm0.03$  & 1.05 \\
 & &MOS2 & 18~000  & 6645--146    & $<$0.4& 1.10 (fix)& $''$ \\
Mar. 2006 &5.54022(3)   &EPN  & 15~506  & 12296--1197   & $0.17\pm0.05$&
$1.11\pm0.03$&  \\
 & &MOS1 & 26~500  & 6539--338  & $0.3\pm0.3$&  $1.48\pm0.06$&0.95 \\
 & &MOS2 & 28~000  & 7119--328 & $0.2\pm0.1$&  $1.02\pm0.02$& $''$  \\
Sep. 2006 &5.54037(1)  &EPN  & 38~505  & 23~842--2974   & $0.13\pm0.03$&$1.07\pm0.02$&   \\
 & &MOS1 & 46~800  & 8113--552  & $0.20\pm0.05$& $1.02\pm0.02$  &1.47 \\
 & &MOS2 & 46~500  & 8836--558  & $0.08\pm0.06$& $0.93\pm0.03$& $''$     \\
Mar. 2007 &5.54041(1)  &EPN  & 37~296  & 21~903--2215   & $0.21\pm0.04 $&$1.07\pm0.02$ &  \\
 & &MOS1 & 63~000  & 4410--1897 & $0.14\pm0.04  $& $0.93\pm0.02$&0.99 \\
 & &MOS2 & 53~000  & 4635--522  & $0.15\pm0.05 $&  $1.10\pm0.02$& $''$\\
Sep. 2007 &5.540~472(7)  &EPN  & 59~014  & 34~386--4117 & $0.18\pm0.02$&$1.04\pm0.06$ &  \\
 & &MOS1 & 67~910  & 11~038--752  & $0.17\pm0.04$& $1.09\pm0.02$  & 1.26\\
  & &MOS2 & 68~785  & 12~328--768 & $0.10\pm0.03$& $1.1\pm0.1$ & $''$\\
\hline  
\end{tabular}}
\medskip
$^a$~The nine PN~spectra were fitted together according to the prescription discussed in the
text~(\ref{feature}); the resulting reduced~$\chi^2$ ($\chi^2_{\rm red}$) is 1.09 (1038~d.o.f.), for the 3$BB$$+$edge model.
\end{table}