\begin{table}%t1
  %\centering
\par
  \caption {\label{tab:1}Best power-law fits $M = a \pi R^\gamma$ for various
    extinction thresholds.  } 
    \begin{tabular}{ccccc}
  \hline\hline
  \noalign{\smallskip}
    Threshold $A_0$ & $a$ & $\gamma$ & Scatter & $c$ \\
    (mag) & (${M}_\odot ~{\rm pc}^{-\gamma}$) & & (percent) & \\
    \hline
    $0.1$ & $\phantom{0}41.2$ & $1.99$ & $11\%$ & $2.25$ \\
    $0.2$ & $\phantom{0}73.1$ & $1.96$ & $12\%$ & $2.00$ \\
    $0.5$ & $          149.0$ & $2.01$ & $14\%$ & $1.63$ \\
    $1.0$ & $          264.2$ & $2.06$ & $12\%$ & $1.44$ \\
    $1.5$ & $          379.8$ & $2.07$ & $14\%$ & $1.38$ \\
    \hline
  \end{tabular}
  \tablefoot {Note that because $\gamma \simeq 2$ in all
    cases, the quantity~$a$ can be interpreted as the average mass
    column density of the cloud above the corresponding extinction
    threshold.  The last two columns show the standard
    deviation of the cloud column densities divided by their
    average (relative scatter) and the ratio between the average
    column densities and the minimum column density set by
    the extinction threshold ($c$).}
\end{table}