\begin{table}%t1
%\centering
\par
\caption{\label{tab:obslog}Observing log for {\em Chandra} exposures of Z~CMa.} 
\begin{tabular}{rcccc}
\hline\hline
{ObsID} & {SeqNo} & {Instrument} & {Date [UT]} & {Expo [ks]} \\
\hline
3751  & 200221 & ACIS-S2 & 2003-12-07 22:00 & 38 \\
10845 & 200569 & ACIS-S3 & 2008-12-28 22:48 & 40 \\
\hline 
\end{tabular}
\end{table}