\begin{table}%t2
\par
\caption {\label{xmmlog} Observation log.}
%\centerline
 {\begin{tabular}{lcccccc}
\hline \hline
\noalign{\smallskip}
Source  &  Obs. Date & ks$^{*}$ & cts/s (0.5--5.0~keV) & $r_{\rm ext}$ &Filter & Instrument \\
\noalign{\smallskip}
\hline
\noalign{\smallskip}
NGC~2954 &    2004 11 03  &  29.4/30.3/19.5 &
($1.42 \pm 0.37$/$1.58 \pm 0.36$/$6.21\pm 0.87$)~$\times 10^{-3} $  & 30\arcsec &  Medium &  MOS1/MOS2/pn  \\
NGC~7785 &    2004 06 14  &  22.0/23.0/14.6 &
($4.73\pm 0.25/4.59\pm 0.23$/$19.7 \pm 0.53$)~$\times 10^{-2}$ & 120\arcsec&  Thin   &    MOS1/MOS2/pn  \\
NGC~7052 &    2002 09 21  &  9.63 &  ($7.38 \pm 0.31$)~$\times 10^{-2} $   & 50\arcsec&  -- &    ACIS-S \\
NGC~6172 &    1999 02 15  & 57.2/52.1  &                --                                &
90\arcsec &  --  &    GIS/SIS  \\
\hline 
\end{tabular}}
\par
\smallskip
$^{*}$ { Live time of the central CCD after cleaning from high background flaring events
(see text).}
\end{table}