\begin{table}%t3
%\centering
\par
\caption{\label{extrema}Results of the period search for the measured lines.}
\small 
\begin{tabular}{lcrccrlc}
\hline\hline
Ion & $N$ & Mean
&Extrema&$\pm$$2\sigma$& $P$ [d] & Ampl. &  $\sigma$\ \\
\hline
Fe~{\sc i} &7&0.502&0.466--0.557&23&13.6&0.0274&0.027 \\
Fe~{\sc ii}&8&1.029&0.982--1.057&23& 9.9&0.0229&0.024 \\  
Ti~{\sc ii}&5&0.506&0.477--0.547&23&55.1&0.0189&0.019 \\
Cr~{\sc ii}&3&0.237&0.197--0.272&22& 2.3&0.0189&0.018 \\
Zr~{\sc ii}&1&0.036&0.028--0.042&23&24.9&0.0066&0.007 \\
Ba~{\sc ii}&1&0.138&0.122--0.164&22&16.3&0.0091&0.009 \\
\hline
\end{tabular} 
\end{table}