\begin{table}%t1
\caption{\label{jo}Journal of observations.}
%\centering  
%\setlength{\tabcolsep}{4.3pt}
\small\begin{tabular}{lcccc}
\hline\hline
Object & Observation & Camera & Exposure & Roll angle\\[2pt]
       & date        &        & time (ks)& (deg)\\
\hline
\rxzerohuit   & 2002-02-23 & ACIS-I & 17.7 & 322.4  \\
\rxzerohuit   & 2005-02-18 & ACIS-I & 19.7 & 325.6  \\
\rxzeroquatre & 2002-11-11 & ACIS-S & 19.4 & 18.6 \\
\rxzeroquatre & 2005-11-07 & ACIS-S & 19.7 & 23.6 \\
\rbsdouze     & 2002-05-21 & ACIS-I & 19.5 & 226.5 \\
\rbsdouze     & 2007-05-12 & ACIS-I & 20.2 & 226.7 \\
\hline
\end{tabular}
\end{table}