\begin{table}%t1
\caption{10 January 2007 observation. The exposure time was $20$~$\times$ $2$~s.}
\label{tab1}
%\centering
\small
\begin{tabular}{c c c c c c c c}
\hline\hline
Slit & UT & Position & Comet & Comet & D2 & Maximum & Sky \\
N$\degr$ & & & Sun velocity & Earth velocity & $g$-factor & Continuum & \\
 & & & (km~s$^{-1}$) & (km~s$^{-1}$) & (s$^{-1}$) & (kR/$\AA$) & (kR/$\AA$) \\
\hline
3 & 15.59.53 & Centred on peak &  --32.05 & --74.62 & 242.6 & 887 & 13~076 \\
  & & of Na emission &  & & & & \\
6 & 16.28.59 & Centred on peak &  --31.83 & --74.51 & 242.8 & 257 & 14~015 \\
  & & of Na emission &  & & & & \\
7 & 17.53.09 & Centred on peak & --31.19 & --74.21 & 243.6 & 2403 & 231~544  \\
  & & of Continuum+sky &  & & & & \\
  & & Emission &  & & & & \\
\hline
\end{tabular}
\end{table}