\begin{table}%t1
\caption{The values of the parameters $\bt$ and $\epsilon_{\rm eff}$ 
(see Eq.~(\ref{FKNapprox})) for
two different photon energy distributions.}
%\footnote{ a (possibly diluted) Planckian 
%of temperature $T$, or, equivalently a mono-energetic distribution 
%with energy 
%$\epso = 2.8kT/\melec c^2$, and a power-law photon field with spectral index 
%$\al_0 \equiv -\diff \ln u_{\epso}/\diff \ln \epso$. For the case where 
%$-0.5<\al_0<1$, it is further 
%assumed that $\epsmin/\epsmax \ll 1$. All approximations are valid for 
%$4\gm\epsilon_{\rm eff} < 10^4$.}
%\centering
\par
{\small 
\begin{tabular}{l|cc}
\hline\hline
Photon distribution & $\bt$ & $\epsilon_{\rm eff}$  \\
\hline \noalign{\smallskip}
Planck, temperature $T$ & $-3/2$ & $2.8kT/\melec c^2$   \\
power law, $\al_0<-0.5$ & $-3/2$ & $\epsmax$   \\
power law, $-0.5<\al_0<1$ & $\al_0-1$& $ \epsmax$   \\
power law, $\al_0>1$ & $-3/2$ & $ \epsmin$  
\\
\hline
\end{tabular}}
\label{table1}
\end{table}