\begin{table}
\caption{\label{tabn2hp21}Hyperfine components and $A_{ul}$ Einstein spontaneous emission coefficients of the \jdub transition of N$_2$H$^+$.}
\small%\centerline
 {
\begin{tabular}{cccccccc}
\hline\hline
  $J'$ & $F_1'$ &  \multicolumn{2}{c}{$F' \rightarrow J$}  & $F_1$ & $F$ & \multicolumn{1}{c}{Frequency$^{{a}}$} & \multicolumn{1}{c}{$A_{ul}$} \cr
  &&&&&& \multicolumn{1}{c}{(MHz)}& \multicolumn{1}{c}{(s$^{-1}$)}\cr
 \hline
2&2&2&1&2&1&186~342.4666& $1.306(-5)$\\
2&2&2&1&2&3&186~342.6570& $1.354(-5)$\\
2&2&1&1&2&1&186~342.7883& $6.530(-5)$\\
2&2&3&1&2&3&186~342.9123& $7.739(-5)$\\
2&2&2&1&2&2&186~342.9537& $6.046(-5)$\\
2&1&1&1&0&1&186~343.0459& $1.935(-4)$\\
2&2&3&1&2&2&186~343.2091& $9.674(-6)$\\
2&1&2&1&0&1&186~343.2577& $1.935(-4)$\\
2&2&1&1&2&2&186~343.2755& $2.177(-5)$\\
2&1&0&1&0&1&186~343.5098& $1.935(-4)$\\
2&2&2&1&1&1&186~344.3808& $1.959(-4)$\\
2&3&3&1&2&3&186~344.4444& $3.870(-5)$\\
2&2&2&1&1&2&186~344.5158& $6.530(-5)$\\
2&2&1&1&1&1&186~344.7026& $1.088(-4)$\\
2&3&3&1&2&2&186~344.7412& $3.096(-4)$\\
2&3&2&1&2&1&186~344.7615& $2.925(-4)$\\
2&2&3&1&1&2&186~344.7711& $2.612(-4)$\\
2&2&1&1&1&2&186~344.8375& $7.255(-6)$\\
2&3&4&1&2&3&186~344.8419& $3.483(-4)$\\
2&3&2&1&2&3&186~344.9519& $1.548(-6)$\\
2&2&1&1&1&0&186~345.1343& $1.451(-4)$\\
2&3&2&1&2&2&186~345.2487& $5.417(-5)$\\
2&1&1&1&2&1&186~345.3441& $2.418(-6)$\\
2&1&2&1&2&1&186~345.5559& $9.674(-8)$\\
2&1&2&1&2&3&186~345.7462& $8.126(-6)$\\
2&1&0&1&2&1&186~345.8080& $9.674(-6)$\\
2&1&1&1&2&2&186~345.8312& $7.256(-6)$\\
2&1&2&1&2&2&186~346.0430& $1.451(-6)$\\
2&1&1&1&1&1&186~347.2584& $3.628(-5)$\\
2&1&1&1&1&2&186~347.3933& $6.046(-5)$\\
2&1&2&1&1&1&186~347.4701& $3.628(-5)$\\
2&1&2&1&1&2&186~347.6050& $1.088(-4)$\\
2&1&1&1&1&0&186~347.6901& $4.837(-5)$\\
2&1&0&1&1&1&186~347.7222& $1.451(-4)$\\
\hline
\end{tabular}}
\medskip
$^{{a}}$ The frequency uncertainty is $\pm$2.3 kHz for all hyperfine components. 
\end{table}