\begin{table}%T3
\caption{\label{n2h}Line parameters of the N$_2$H$^+$ and N$_2$D$^+$ lines.}
\small%\centerline
{
\begin{tabular}{lccccccccccc}
\hline\hline
& \multicolumn{4}{c}{N$_2$H$^+$~(1--0)} &  &\multicolumn{6}{c}{N$_2$D$^+$} \\
\cline{2-5} \cline{7-12} 
Source & $W$ & $\Delta v$  & $\tau$ & $T_{\rm ex}$ & $T_{\rm Kin}$ & $W_{J=1{-}0}$& $W_{J=2{-}1}$  & $W_{J=3-2}$ & $\tau$ & $ \Delta v_{2-1}$ &  $T_{\rm ex}$ \\ 
 & [K~km~s$^{-1}$] & [km~s$^{-1}$] & & [K] & [K] & [K~km~s$^{-1}$] & [K~km~s$^{-1}$] & [K~km~s$^{-1}$]& $J=2{-}1$ & [km~s$^{-1}$] &[K] \\
\hline 
L 1448 IRS 2 & 12.93 & 0.50 & 11.6 & 6.8 & -- & 1.7 & 1.10 & 0.73 & $<$0.1 &    0.53 &                       --          \\
L 1448 IRS 3 & 24.65 & 0.93& 4.1 & 11.4 & 12.0 & 4.0 & 5.05  & 3.22 & 2.6 &   0.59 &                    7.9       \\
L 1448 C & 12.48 & 0.76& 5.3 & 7.3 & 13.7$^*$ & $<$1 & 2.32 & 1.38 & $<$0.1 &      0.72 &                       --          \\
L 1455 A1 & 7.20 &0.74 & 1.4 & 9.2 & 15.0 & $<$1 & 0.68 & $<$0.74 & $<$0.1 &  0.42 &               --     \\
L 1455 A2 & 8.60 &0.54 & 3.0 & 9.1 & 11.0 & $<$1 & 1.03 & $<$0.73 &  $<$0.1 & 0.33 &              --    \\
Per 4 S & 5.08 &0.29 & 3.5 & 8.5 & 9.0 & 1.3 &1.43 &  0.98 & $<$0.1 &     0.32 &                 --          \\
Per 4 N & 4.62 & 0.31& 3.6 & 7.6 & 10.0 &  1.3 & 0.75 & $<$0.68 &  $<$0.1 &    0.31 &           --       \\
Per 5 & 7.53 & 0.38 & 3.8 & 8.7 & 11.0 &$<$1 & 1.07  & 1.08 &  $<$0.1 &   0.36 &                 --            \\
Per 6 & 4.64 & 0.36 & $<$0.1 & -- & 11.0 &$<$1 & $<$0.18 & $<$0.69 & -- &  --   &                   --           \\
IRAS 03282 & 9.53 & 0.38& 5.3 & 8.6 & 11.3$^*$ & $<$1 & 3.58 & 1.47 & 3.9 &  0.34 &                    7.9         \\
Barnard 1-B & 19.05 &0.82 & 8.6 & 7.6 & 12.0 & 5.9& 7.48 & 4.82 & 4.9 &  0.78    &                   6.7          \\
HH 211 & 9.18 & 0.41& 6.2 & 7.6 & 12.8$^*$ & 2.3 & 5.24 & 2.08 & 4.9 &   0.39   &                    7.5              \\
Barnard 5 IRS 1 & 8.59 &0.43 & 6.4 & 7.2 & 10.8$^*$ & $<$1 & 0.50 & 0.65 & $<$0.1 & 0.50 &            --  \\
L 1527 & 3.91 & 0.32& 5.6 & 5.7 & 10.8$^*$ & $<$1& $<$0.18 & $<$0.59 & --  &   -- &                    --           \\
L 483 & 14.05 & 0.44& 12.1 & 7.3 & 10.0 & 2.1 & 1.75  & 1.13 & 2.8 &     0.37   &                5.5              \\
SMM 5 & 15.39 &0.70 & 4.9 & 8.9 & 12.0 & $<$1 & 2.46 & 1.43 &  $<$0.1  &     0.58 &                       --           \\
L 723 & 5.70 & 0.71& 2.4 & 6.6 & 11.0 & $<$1 & 0.34 & 1.29 & $<$0.1  &     0.32 &                        --            \\
L 673 A & 7.34 &0.54 & 2.9 & 8.6 & $<$12.0 & $<$1 & 0.45 & 0.63 & $<$0.1  &    0.34 &                          --          \\
B 335 & 6.05 & 0.40& 9.0 & 5.7 & 9.9 & $<$1 & 0.42 & 0.42 & $<$0.1 &     0.46    &                        --               \\
L 1157 & 8.38 &0.65 & 2.1 & 8.9 & -- & $<$1& 0.53 & 1.00 & $<$0.1 &      0.56 &                        --                \\
\hline
\end{tabular}}
\smallskip
The kinetic gas temperatures marked with an $^*$ are taken from Hatchell~(\cite{nh3}). All other $T_{\rm kin}$ values are listed in Jijina et~al.~(\cite{jij}). The errors on the integrated intensities of N$_2$H$^+$~1$-$0 and N$_2$D$^+$~2$-$1 are $\sim$$10\%$ (calibration uncertainties), whereas the errors on the N$_2$D$^+$~1$-$0 and N$_2$D$^+$~3$-$2~lines are dominated by the noise of the spectra (0.5 and 0.2~K~km~s$^{-1}$ for $J=1{-}0$ and $J=3{-}2$, respectively). $\tau$ is the total optical depth, defined as the sum of the optical depths of the individual hyperfine components. Typical errors of $\tau$ are $\pm$$0.5$ and $\pm$$0.2$ for N$_2$H$^+$ and N$_2$D$^+$~2$-$1 (where it is detected), respectively. The resulting error of $T_{\rm ex}$ is $\sim$$0.2$~K for both species.
\end{table}