\begin{table}%t1
\caption{Water production rate measurements of 46P/Wirtanen.}
\label{Table_qh2o}
%\centerline
{
\begin{tabular}{lllll}
\hline
\hline
        &Bertaux et~al. (\cite{Bertaux1999}) &Fink et~al. (\cite{Fink1998})  &Farnham et~al. (1998)  &Stern et~al. (\cite{Stern1998})\\
\hline
Instrument  &SOHO-SWAN   &1.54 m Catalina &1.1 m and 0.8 m at Lowell Obs. &HST-FOS\\
Method    &Ly-$\alpha$    &OI$^1$D (6300 \AA) &OH$^a$ &OH\\
Model     &Haser  &Haser  &A'Hearn (1995) &Vectorial (Festou \cite{Festou1981})\\
$r_{\rm h}$ range (pre)  &1.52--1.07    &1.22--1.07      &1.14--1.08 &2.72--1.31\\
$r_{\rm h}$ range (post) &1.07--1.35    &1.08--1.47      & none  & none \\
Accuracy         &25\%  &20\% & See footnote $b$  & See footnote $b$ \\
\hline
\end{tabular}}  
\medskip
$^{\rm a}$ We derived $Q_{\rm{H_2O}}$ using $Q_{\rm{H_2O}}=1.3\times Q_{\rm{OH}}$, as suggested by the authors. \\
$^{\rm b}$ The accuracy depends on each water production rate measurement (see Fig.~\ref{water_production}).
\end{table}