\begin{table}%tA.2 \caption{\label{t:sensitivitym15}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 GIRAFFE.} %\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 & 0.05 & 0.07 & 0.077 & & \\ Systematic& & 38 & 0.06 & 0.04 & 0.01 & & & \\ \hline $[$Fe/H$]${\sc i}& 38 & +0.055 & +0.006 &$-$0.004 & $-$0.031 & +0.012 &0.026 &0.042 \\ $[$Fe/H$]${\sc ii}& 3 & $-$0.044 & +0.092 & +0.027 & $-$0.008 & +0.044 &0.050 &0.047 \\ $[$O/Fe$]${\sc i}& 1 & $-$0.041 & +0.074 & +0.036 & +0.029 & +0.077 &0.083 &0.055 \\ $[$Na/Fe$]${\sc i}& 3 & $-$0.009 & $-$0.051 &$-$0.029 & +0.022 & +0.044 &0.050 &0.041 \\ $[$Mg/Fe$]${\sc i}& 2 & $-$0.014 & $-$0.015 &$-$0.005 & +0.017 & +0.054 &0.056 &0.024 \\ $[$Si/Fe$]${\sc i}& 7 & $-$0.059 & +0.024 & +0.012 & +0.025 & +0.029 &0.035 &0.047 \\ $[$Ca/Fe$]${\sc i}& 7 & +0.017 & $-$0.029 &$-$0.013 & $-$0.013 & +0.029 &0.032 &0.020 \\ $[$Sc/Fe$]${\sc ii}& 6 & $-$0.061 & +0.068 & +0.031 & +0.010 & +0.031 &0.038 &0.052 \\ $[$Ti/Fe$]${\sc i}& 5 & +0.039 & $-$0.016 &$-$0.014 & +0.008 & +0.034 &0.036 &0.034 \\ $[$V/Fe$]${\sc i} & 6 & +0.056 & $-$0.015 &$-$0.015 & +0.013 & +0.031 &0.034 &0.047 \\ $[$Cr/Fe$]${\sc i}& 4 & +0.020 & $-$0.018 &$-$0.009 & +0.024 & +0.039 &0.042 &0.020 \\ $[$Co/Fe$]${\sc i}& 1 & +0.004 & +0.009 & +0.007 & +0.025 & +0.077 &0.079 &0.010 \\ $[$Ni/Fe$]${\sc i}& 8 & $-$0.014 & +0.014 & +0.009 & +0.021 & +0.027 &0.031 &0.013 \\ \hline \end{tabular} \end{table}