\begin{table}%t1
%\centering
\par
\caption{Convolution function factor.}\label{tab:convfunc}
\small 
\begin{tabular}{llccc}
\hline\hline
&& \multicolumn{2}{c}{\textsf{Function Form}} & \\
\textsf{Function} & \textsf{Parms} & \textsf{$\eta$ Linear} &
\textsf{$\eta$ Circular} & \textsf{$R_{\rm support}$} \\
\hline
Pill Box &
\ldots & 1.00 & 0.78 & 0.5 \\
$\exp\left[-\left(\frac{|z|}{b}\right)^2\right]$ &
$b$ = 1.00 & 3.14 & 3.14 & 3.0 \\
$\frac{\sin\left(\frac{\pi |z|}{a}\right)}{\frac{\pi |z|}{a}}$ &
$a$ = 1.14 & 1.36 & 1.16 & 3.0 \\
$\frac{\sin\left(\frac{\pi |z|}{a}\right)}{\frac{\pi |z|}{a}}\times
{\exp\left[-\left(\frac{|z|}{b}\right)^2\right]}$ &
$a$ = 1.55, $b$ = 2.52 & 2.33 & 1.43 & 3.0 \\
$\frac{J_1\left(\frac{|z|}{c}\right)}{\frac{|z|}{c}}\times
{\exp\left[-\left(\frac{|z|}{b}\right)^2\right]}$ &
$b$ = 2.52, $c$ = 1.55 & 3.59 & 3.03 & 3.0 \\
\hline
\end{tabular}
\end{table}