\begin{table}%T1
\caption{MOS2 count rate to flux conversion factors.}\label{t1}
%\centerline
{
\begin{tabular}{rrll}
\hline \hline
$\alpha_{\rm E}$      & {\it HR}2       & Flux (0.5$-$4.5~keV)   & Flux  (4.5$-$7.5~keV) \\
              &           & $10^{-12}$~\ecs      & $10^{-11}$~\ecs    \\
(1)           & (2)       & (3)                  & (4)                \\
\hline
$-$3.0         & 0.77      & 14.3; 14.4; 15.0   &  4.53; 4.54; 4.59   \\
$-$2.0         & 0.56      & 12.8; 12.9; 13.6   &  4.24; 4.25; 4.30    \\
$-$1.0         & 0.22      & 10.6; 10.8; 11.7   &  3.97; 3.97; 4.03    \\
$-$0.5         & 0.01      &  9.47;  9.61; 10.6   &  3.84; 3.84; 3.90    \\
 0.0           & $-$0.22   &  8.35;  8.49;  9.55  &  3.71; 3.72; 3.77     \\
 0.4           & $-$0.38   &  7.56;  7.70;  8.82  &  3.62; 3.62; 3.68     \\
 0.5           & $-$0.42   &  7.38;  7.53;  8.66  &  3.59; 3.60; 3.65     \\
 0.7           & $-$0.49   &  7.06;  7.20;  8.37  &  3.55; 3.55; 3.61     \\
 0.9           & $-$0.57   &  6.78;  6.92;  8.11  &  3.50; 3.51; 3.56     \\
 1.0           & $-$0.60   &  6.65;  6.79;  8.00  &  3.48; 3.49; 3.54     \\
 1.5           & $-$0.74   &  6.16;  6.31;  7.61  &  3.38; 3.38; 3.43     \\
 2.0           & $-$0.83   &  5.89;  6.04;  7.46  &  3.28; 3.28; 3.33     \\
 3.0           & $-$0.94   &  5.75;  5.94;  7.62  &  3.10; 3.10; 3.15     \\
\hline
\end{tabular}}
\par
\medskip
Columns are as follows: (1) Energy spectral index
($S_{\rm E} \propto E^{-\alpha_{\rm E}}$); (2)~corresponding hardness
ratio {\it HR}2 computed as discussed in
Sect.~3.3; (3) Flux (corrected for Galactic absorption) in the
0.5$-$4.5~keV energy band corresponding to an observed count rate of
1 cts/s in the same energy band. The three numbers refer to thin,
medium and thick filters; (4) Flux (corrected for Galactic
absorption) in the 4.5$-$7.5~keV energy band corresponding to an
observed count rate of 1 cts/s in the same energy band. The three
numbers refer to thin, medium and thick filters. 
NOTE -- A Galactic absorbing column density of $3\times 10^{20}$~cm$^{-2}$,
the median value for the XMM-Newton fields used here, has been
assumed. Given the range of the Galactic absorbing column density along the
line of sight (from ${\sim} 5\times 10^{19}$ to $10^{21}$~cm$^{-2}$)
the  CR2F in the 0.5$-$4.5~keV energy range are accurate to~$\pm $18\%; 
the CR2F in the 4.5$-$7.5~keV energy range  are independent of
the Galactic~$N_{\rm H}$. 
Please note that in the case of sources having extreme {\it HR}2 values 
the observed spectra could be much more complex than a simple power law; 
for these sources the conversion factor reported in the table should 
be considered only
 as indicative and a proper X-ray spectral analysis is needed.
\end{table}