\begin{table}%t3
      \caption{Effective wavelengths, extinction ratios, and counts-to-flux conversion factors for the UVOT filters.}
         \label{uvot_filters}
         %\centering
\small
         \begin{tabular}{lccc}
            \hline
            \noalign{\smallskip}
Filter & $\lambda_{\rm eff}^{{a}}$ & $A_{\lambda_{\rm eff}}/E(B-V)^{{b}}$ & $F_{\rm conv}^{{c}}$  \\
            \noalign{\smallskip}
            \hline
            \noalign{\smallskip}
$V$    & 5460 & 3.2 & (2.2 $\pm$ 0.1) $\times 10^{-16}$   \\
$B$    & 4350 & 4.2 & (1.3 $\pm$ 0.1) $\times 10^{-16}$   \\
$U$    & 3450 & 5.2 & (1.5 $\pm$ 0.06) $\times 10^{-16}$   \\
$UVW1$ & 2600 & 6.7 & (3.5 $\pm$ 0.07) $\times 10^{-16}$   \\
$UVM2$ & 2200 & 9.7 & (7 $\pm$ 1) $\times 10^{-16}$   \\
$UVW2$ & 1930 & 8.3 & (6.0 $\pm$ 0.4) $\times 10^{-16}$   \\
                         \hline
         \end{tabular}
\begin{list}{}{}
\item[$^{{a}}$] Effective wavelength of the filter in \AA.
\item[$^{{b}}$] Ratio of $A_{\lambda_{\rm eff}}$, the extinction in
magnitudes at the effective wavelength of the filter $\lambda_{\rm eff}$, to
$E(B-V)$. For the UV filters ($UVW1$, $UVM2$ and $UVW2$) $A_{\lambda_{\rm eff}}/E(B-V)$ was
obtained from Fig.~1 in \citet{seaton1979}, and for the optical ($V$, $B$ and $U$)
filters the values are derived from the interstellar reddening curve given by  \citet{zombeck1990}.
\item[$^{{c}}$] Conversion factor from rate (Counts~s$^{-1}$) to flux
(erg~cm$^{-2}$~s$^{-1}$~\AA$^{-1}$) from UVOT in-orbit calibration as of 30 June
2005 (T.S. Poole, priv. comm.).
\end{list}
\end{table}