\begin{table}%ta5
\caption{\label{tab:ironlines}Detections and upper limits on the equivalent width of iron lines for 3C~$273$ (3EG~J$1229+0210$). 
The continuum is best fitted with the broken power law model with Galactic absorbtion reported in Table~\ref{tab:srcdata2}. 
Columns: 
(1) equivalent width [eV] for $E=6.4$~keV and $\sigma=0.15$~keV;
(2) $\Delta \chi^2$ with respect to the best fit continuum (2~d.o.f.);
(3) equivalent width [eV] for $E=6.4$~keV and $\sigma=0.5$~keV;
(4) $\Delta \chi^2$ with respect to the best fit continuum (2~d.o.f.);
(5) equivalent width [eV] for $E=6.7$~keV and $\sigma=0.15$~keV;
(6) $\Delta \chi^2$ with respect to the best fit continuum (2~d.o.f.);
(7) equivalent width [eV] for $E=6.7$~keV and $\sigma=0.5$~keV;
(8) $\Delta \chi^2$ with respect to the best fit continuum (2~d.o.f.);
The uncertainties in the parameters and upper limits estimate are at the $90\%$ confidence limits for~1~parameter.}
\small%\centering
\par
\begin{tabular}{cccccccc}
\hline\hline
\multicolumn{4}{c}{$E=6.4$~keV} & \multicolumn{4}{c}{$E=6.7$~keV} \\
$\sigma=0.15$~keV  & $\Delta \chi^2$ & $\sigma=0.5$~keV & $\Delta \chi^2$ &  $\sigma=0.15$~keV & $\Delta \chi^2$ & $\sigma=0.5$~keV & $\Delta \chi^2$ \\
(1)                & (2)             & (3)              & (4)             & (5)                & (6)             & (7)              & (8)   \\
\hline
$\rm 29_{-12}^{+13}$   & $14.3$          & $54.5\pm 0.1$    & $20.2$          & $18.4\pm 0.1$      & $5.2$           & $39.3\pm 0.1$    & $7.7$\\
$<$$16$              & $-$             & $<$$50$            & $-$             & $<$$28$              & $-$             & $<$$53$            & $-$\\
$<$$19$              & $-$             & $<$$62$            & $-$             & $31\pm 19$         & $7.2$           & $<$$64$            & $-$\\
$\rm 20_{-12}^{+13}$   & $7.0$           & $\rm 46_{-15}^{+33}$ & $16.0$          & $\rm 21_{-14}^{+13}$   & $6.4$           & $\rm 62_{-36}^{+15}$ & $12.5$\\
$<$$20$              & $-$             & $\rm 38_{-13}^{+27}$ & $16.2$          & $22\pm 11$         & $10.8$          & $\rm 48_{-28}^{+13}$ & $12.0$\\
$<$$37$              & $-$             & $<$$59$            & $-$             & $<$$46$              & $-$             & $<$$83$            & $-$\\
$<$$56$              & $-$             & $<$$87$            & $-$             & $<$$30$              & $-$             & $<$$95$            & $-$\\
$<$$38$              & $-$             & $<$$105$           & $-$             & $<$$41$              & $-$             & $<$$113$           & $-$\\
$\rm 44_{-37}^{+40}$   & $3.3$           & $<$$117$           & $-$             & $<$$42$              & $-$             & $<$$133$           & $-$\\
$<$$62$              & $-$             & $\rm 80_{-67}^{+49}$ & $4.1$           & $\rm 64_{-37}^{+34}$   & $8.6$           & $\rm 110_{-83}^{+44}$& $5.8$\\
$<$$52$              & $-$             & $<$$144$           & $-$             & $<$$75$              & $-$             & $<$$156$            & $-$\\
$<$$42$              & $-$             & $<$$111$           & $-$             & $<$$60$              & $-$             & $<$$112$            & $-$\\
$<$$60$              & $-$             & $<$$106$           & $-$             & $\rm 43_{-35}^{+34}$   & $4.1$           & $<$$92$             & $-$\\
$<$$40$              & $-$             & $<$$97$            & $-$             & $<$$55$              & $-$             & $<$$125$            & $-$\\
$<$$40$              & $-$             & $\rm 33_{-26}^{+68}$ & $3.8$           & $<$$47$              & $-$             & $\rm 33_{-27}^{+74}$  & $3.7$\\
\hline
\end{tabular}
\end{table}