\begin{table}%t3
\par
\caption{\label{table:3}Production rates and mixing ratios of comet 8P/Tuttle.} 
%\centerline
 {\begin{tabular}{c c c c }       % centered columns (4 columns) 
\multicolumn{4}{c}{January 28, 2008} \\\hline\hline                 % inserts double horizontal lines 
Molecules & $T_{\rm rot}$ & Production rate & Mixing ratio \\ 
~     
    & [K] & [molecules s$^{-1}$] & [\%] \\ 
\hline 
H$_{2}$O       & 70~$\pm$~15 & (4.6~$\pm$~0.4)~$\times$~$10^{28}$ & 100            \\ % inserting body of the table 
HCN            & 54~$\pm$~9  & (3.4~$\pm$~1.1)~$\times$~$10^{25}$ & 0.07~$\pm$~0.02  \\ % inserting body of the table 
C$_{2}$H$_{2}$ & (70)$^*$  & (2.1~$\pm$~0.7)~$\times$~$10^{25}$ & 0.05~$\pm$~0.02  \\ % inserting body of the table 
\hline 
\end{tabular}} 
\par
%\centerline
 {\begin{tabular}{c c c c }       
 \multicolumn{4}{c}{February 4, 2008} \\ 
\hline\hline                 % inserts double horizontal lines 
Molecules & $T_{\rm rot}$ & Production rate & Mixing ratio \\ 
~         & [K] & [molecules s$^{-1}$] & [\%] \\ 
\hline 
H$_{2}$O       & 65$^{+15}_{-13}$ & (3.0~$\pm$~0.2)~$\times$~$10^{28}$ & 100            \\ % inserting body of the table 
CH$_{4}$       & (70)$^*$         & (1.7~$\pm$~1.1)~$\times$~$10^{26}$ & 0.6~$\pm$~0.4    \\ % inserting body of the table 
C$_{2}$H$_{6}$ & (70)$^*$         & (6.7~$\pm$~1.3)~$\times$~$10^{25}$ & 0.23~$\pm$~0.04  \\ % inserting body of the table 
CH$_{3}$OH     & (70)$^*$         & (9.7~$\pm$~1.3)~$\times$~$10^{26}$ & 3.3~$\pm$~0.4    \\ \hline 
\end{tabular} }
\smallskip
$^*$ This value is adopted, and is based on H$_{2}$O measurements (see text).
\end{table}