\begin{table}%t4
\caption{Alternate angular units.}
\label{angular_units}
%\centering
\par
\begin{tabular}{lll}
\hline \hline
Unit String	& Meaning		& Notes\\
\hline
{\tt deg}	& degree of arc		& $\pi/180$ radians\\
{\tt arcmin}	& minute of arc		& 1/60 degree\\
{\tt arcsec}	& second of arc		& 1/3600 degree\\
{\tt mas}	& millisecond of arc	& 1/3~600~000 degree\\
{\tt rad}	& radian		& $180/\pi$ degrees\\
\hline
\end{tabular}
\end{table}