\begin{table}%t5
\caption{\label{table:ISM_abundances}Average ISM abundances in units of the protosolar values \citep{Lodders} and calculated by summing contribution from all ISM phases.}             % title of Table                          % used for centering table
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\par
\par
\begin{tabular}{lccccc}
\hline\hline\noalign{\smallskip}
X                      &  O                & Ne             & Mg            & Fe            & N\tablefootmark{e}       \\
\hline
\object{GS 1826-238}\tablefootmark{a}   &  $1.23\pm0.05$    & $1.75\pm0.11$  & $2.45\pm0.35$ & $1.37\pm0.17$ & $2.4\pm0.7$      \\
Crab\tablefootmark{b}          &  $1.030\pm0.016$  & $1.72\pm0.11$  & $0.85\pm0.21$ & $0.78\pm0.05$ & $1.01\pm0.09$    \\
Cyg X-2\tablefootmark{c}       &  0.6--0.8        & 0.8--1.1      & 0.6--1.1     &--             & --                \\
\object{4U 1820-303}\tablefootmark{d}   &  0.7--1.1        & 1.1--2.0      & --             & 0.3--0.8     & --                \\
\hline
\end{tabular}
\tablefoot{\tablefoottext{a}{Model C, gas + dust.}
\tablefoottext{b}{\cite{kaastra} Model B, gas + dust.}
\tablefoottext{c}{\cite{yao09}.}
\tablefoottext{d}{\cite{JuettII}.}
\tablefoottext{e}{Estimated through a local fit in the 27--33~{\AA} range.}}%, see Sect.~\ref{section:ISM_abundances}.
\vspace*{-2mm}\end{table}