\begin{table}%tA.1
\caption{\label{t:sensitivityu15}Sensitivities of abundance ratios to variations in the atmospheric
parameters and to errors in the equivalent widths, and errors in abundances for stars in M~54 observed with UVES.}
%\centering
\par
\begin{tabular}{lrrrrrrrr}
\hline \hline \noalign{\smallskip}
Element     & Average  & $T_{\rm eff}$ & $\log g$ & [A/H]   & $v_t$    & $EW$s     & Total   & Total      \\
            & n. lines &      (K)      &  (dex)   & (dex)   &km~s$^{-1}$& (dex)   &Internal & Systematic \\
\hline        
Variation&             &  50           &   0.20   &  0.10   &  0.10    &         &         &            \\
Internal &             &   5           &   0.04   &  0.06   &  0.05    & 0.060   &         &            \\
Systematic&            &  38           &   0.06   &  0.05   &  0.02    &         &         &            \\
\hline
$[$Fe/H$]${\sc  i}& 70 &   +0.056      & $-$0.045 &$-$0.001 & $-$0.026 & +0.007  &0.018    &0.050      \\
$[$Fe/H$]${\sc ii}&  8 &   +0.077      &   +0.095 &  +0.031 & $-$0.011 & +0.021  &0.035    &0.090      \\
$[$O/Fe$]${\sc  i}&  2 & $-$0.042      &   +0.070 &  +0.034 &   +0.025 & +0.042  &0.051    &0.182      \\
$[$Na/Fe$]${\sc i}&  3 & $-$0.007      & $-$0.055 &$-$0.034 &   +0.015 & +0.035  &0.042    &0.149      \\
$[$Mg/Fe$]${\sc i}&  3 & $-$0.020      & $-$0.017 &$-$0.006 &   +0.016 & +0.035  &0.036    &0.037      \\
$[$Al/Fe$]${\sc i}&  2 & $-$0.011      & $-$0.023 &$-$0.009 &   +0.015 & +0.042  &0.044    &0.255      \\
$[$Si/Fe$]${\sc i}&  8 & $-$0.065      &   +0.020 &  +0.010 &   +0.020 & +0.021  &0.025    &0.058      \\
$[$Ca/Fe$]${\sc i}& 17 &   +0.014      & $-$0.025 &$-$0.018 & $-$0.014 & +0.015  &0.020    &0.033      \\
$[$Sc/Fe$]${\sc i}&  1 &   +0.036      & $-$0.028 &$-$0.014 &   +0.021 & +0.060  &0.062    &0.059      \\
$[$Sc/Fe$]${\sc ii}& 7 & $-$0.084      & $-$0.020 &$-$0.003 & $-$0.007 & +0.023  &0.025    &0.078      \\
$[$Ti/Fe$]${\sc i}&  9 &   +0.044      & $-$0.020 &$-$0.017 &   +0.004 & +0.020  &0.023    &0.052      \\
$[$Ti/Fe$]${\sc ii}& 1 & $-$0.093      & $-$0.013 &  +0.000 &   +0.007 & +0.060  &0.061    &0.083      \\
$[$V/Fe$]${\sc i} &  8 & $-$0.029      & $-$0.103 &$-$0.113 & $-$0.090 & +0.021  &0.085    &0.054      \\
$[$Cr/Fe$]${\sc i}&  2 &   +0.023      & $-$0.022 &$-$0.013 &   +0.016 & +0.042  &0.044    &0.037      \\
$[$Mn/Fe$]${\sc i}&  3 &   +0.009      & $-$0.017 &$-$0.009 &   +0.000 & +0.035  &0.035    &0.036      \\
$[$Co/Fe$]${\sc i}&  4 & $-$0.018      & $-$0.004 &  +0.001 &   +0.020 & +0.030  &0.032    &0.058      \\
$[$Ni/Fe$]${\sc i}& 20 & $-$0.023      &   +0.012 &  +0.005 &   +0.004 & +0.013  &0.014    &0.020      \\
$[$Cu/Fe$]${\sc i}&  1 & $-$0.031      &   +0.012 &  +0.001 & $-$0.007 & +0.013  &0.060    &0.070      \\
\hline
\end{tabular}
\end{table}