\begin{table}%t7
\par
\caption{\label{table:7}HCN/H$_{2}$O (CN/OH), C$_{2}$H$_{2}$/H$_{2}$O (C$_{2}$/OH), and C$_{2}$H$_{2}$/HCN (C$_{2}$/CN) ratios in comet 8P/Tuttle.} 
%\centering
                          % used for centering table 
\begin{tabular}{c c c c c }       % centered columns (4 columns) 
\hline\hline   
\noalign{\smallskip}              % inserts double horizontal lines 
log$_{10}$[$\frac{Q{\rm(CN)}}{Q{\rm(OH)}}$] & log$_{10}$[$\frac{Q{\rm(C_{2})}}{Q{\rm(OH)}}$]  & log$_{10}$[$\frac{Q{\rm(C_{2})}}{Q{\rm(CN)}}$] &~ & Remarks \\ 
\hline 
--2.54 & --2.39 & 0.15 &~  & 1980 \\ 
--2.58 & --2.41 & 0.17 &~  & 2007 \\ 
~     & ~     & 0.11--0.15 &~  & 2008, \citet{jehin} \\\hline\\[-3mm]
log$_{10}$$\left[\frac{Q{\rm(HCN)}}{Q{\rm(H_{2}O)}}\right]$ & log$_{10}$$\left[\frac{Q{\rm(C_{2}H_{2})}}{Q{\rm(H_{2}O)}}\right]$  
                                                 & log$_{10}$$\left[\frac{Q{\rm(C_{2}H_{2})}}{Q{\rm(HCN)}}\right]$ 
                                                 & log$_{10}$$\left[\frac{Q{\rm(C_{2}H_{2}+C_{2}H_{6}(50\%))}}{Q{\rm(HCN)}}\right]$ & Remarks \\\hline 
$\rm -3.13^{+0.11}_{-0.15}$ & $\rm -3.35^{+0.13}_{-0.17}$ & $\rm -0.22^{+0.17}_{-0.26}$ & $\rm 0.33^{+0.13}_{-0.18}$ & This work \\ 
$\rm -3.14^{+0.04}_{-0.08}$ & $<$--3.41               & $<$--0.26               &~                       & \citet{bonev} \\ 
\hline 
\end{tabular} 
\end{table}