\begin{table}%t2
\caption{Best fit parameters relative to Eq.~(\ref{eq:15}).  If a
    normal reddening law is assumed, the X-factors derived from these
    fits are $\{ 4.21, 3.93, 3.77, 2.91 \} \times 10^{20}~\mbox{cm}^{-2}~\mbox{K}^{-1}~\mbox{km}^{-1}~\mbox{s}$ respectively.  The
    formal, $1\sigma$ errors are $0.002~\mbox{mag}$ and~$0.0002$ for~$A_K^{(0)}$ and~$r$, respectively (for all four fits).}
  \label{tab:2}
  \small%\centering
\par
  \begin{tabular}{lcc}
  \hline\hline\noalign{\smallskip}
    Fit & $A_K^{(0)}$ & $r$ \\
        & (mag)    & ($\mbox{mag K}^{-1}~\mbox{km}^{-1}~\mbox{s}$) \\
    \hline
    Whole sample& 0.176 & 0.0184 \\
    $I_{{}^{12}{\rm CO}} > 5~\mbox{K~km~s}^{-1}$ & 0.199
    & 0.0172 \\ 
    $A_K > 0.1~\mbox{mag}$ & 0.211 & 0.0165 \\
    $A_K \in [0.1, 0.6]~\mbox{mag}$ & 0.226 & 0.0127 \\
    \hline
  \end{tabular}
  \end{table}