\begin{table}%t3
\caption{\label{grav}Spectroscopically and photometrically determined surface gravities.}
%\centering
\small  
  \begin{tabular}{l  c c c}
  \hline\hline
  \noalign{\smallskip}
    Star  &   $\log g_{\rm spec}$   &    $\log g_{\rm photo}$  &  Difference  \\
    & & &  $\log g_{\rm photo}-\log g_{\rm spec}$\\
  \noalign{\smallskip}
    \hline
 {B3-b1}   & 2.0 & 1.7 & $-0.3$ \\
 {B3-b7}  & 2.1  & 1.8 & $-0.3$ \\
 {B3-b8} & 1.5  & 1.7 & $0.2$ \\
 {BW-b6}   & 2.2 & 1.9 & $-0.3$ \\
 {BW-f6}    & 1.5 & 1.8  & 0.2 \\
 {B6-f1}  & 1.3 & 1.6 & 0.3\\
 {B6-b8} &   1.3  & 1.7 & 0.4\\
 {B6-f7}   & 1.9 & 1.8 & $-$0.1\\
 {Arp~4203}   & 0.3   &  0.6 & 0.3\\
 {Arp~4329} & 1.2  & 1.5 & 0.3 \\
 {Arp~1322}   & 1.5 & 1.5 & $-$0.0\\
  \hline
\end{tabular}
\end{table}