\begin{table}%t2
     \caption{\label{tab2}The parameters~$A$, $B$ and~$C$ of the approximate formulae 
 for Stark widths and shifts.}
 %\centering
\par
\begin{tabular}{cccc}
\hline\hline
Line & 5950.2 \AA\ & 6142.48\ \AA\ & 6155.13 \AA\ \\
\hline
\multicolumn{4}{c}{WIDTH} \\
\hline
 \multicolumn{4}{c}{Electrons} \\
\hline
$c_1$ &1E--16 &1E--14 & 1E--14 \\
$A$ & --0.33801648 &--0.87997007&--0.88824105  \\
$B$ & 0.12759724 & 0.01704956&0.01525209  \\
\hline
\multicolumn{4}{c}{Protons} \\
\hline
$c_1$ &1E--16 &1E--15 &1E--15 \\
$A$&--0.81663954 &--0.77664655&--0.76856840  \\
$B$&0.01728187 &0.03913901&0.03758103  \\
\hline
\multicolumn{4}{c}{He\ii} \\
\hline
$c_1$ &1E--16 &1E--15 &1E--15 \\
$A$&--0.83337682  &--0.81987023&--0.81114334  \\
$B$& 0.01297813 &0.02771659&0.02946282   \\
\hline
\hline
\multicolumn{4}{c}{SHIFT} \\
\hline
 \multicolumn{4}{c}{Electrons} \\
\hline
$c_2$ &1E--16 &1E--15 &1E--15 \\
 $A$ & 0.38028502& --0.63997507 &--0.69208568  \\
 $B$ & 1.33496618&0.88440353 & 1.18033516 \\
 $C $& --0.02047206&0.07950743 & 0.04721782 \\
\hline
\multicolumn{4}{c}{Protons} \\
\hline
$c_2$ &1E--16 &1E--15 &1E--15 \\
 $A$ &$-$1.32564473 &1.12387002 &0.17032257 \\
 $B$ &0.01917066 &0.02838789  &0.10512289 \\
 $C$ &1.43394434 &$-$1.31786299 &--0.37318012 \\
\hline
\multicolumn{4}{c}{He\ii} \\
\hline
$c_2$ &1E--16 &1E--15 &1E--15 \\
 $A$ &$-$1.67370868 &0.14785217 &0.14840180 \\
 $B$ &0.01490401 &0.10161093 &0.10439166 \\
 $C$ &1.75773489 &--0.30183339 &--0.31051296 \\
\hline
\end{tabular}
\end{table}