\begin{table}%T1
\caption{The sources and numbers of light curves $NLC$ used to define the classes, their average total time span $\langle T_{\rm tot}\rangle$ and their average number of measurements $\langle N_{\rm points}\rangle$.}
\label{tabel1}
%%\centering
\par
\small
\begin{tabular}{cccc}
\hline\hline
Instrument&$NLC$&$\langle T_{\rm tot}\rangle$ (days)&$\langle N_{\rm points}\rangle$\\
\hline
HIPPARCOS&$1044$&$1097$&$103$\\
GENEVA&$118$&$3809$&$175$\\
OGLE&$527$&$1067$&$329$\\
ULTRACAM&$19$&$22$&$15~820$\\
MOST&$3$&$34$&$59~170$\\
WET&$3$&$5.6$&$11~643$\\
ROTOR&$3$&$5066$&$881$\\
CFHT&$3$&$0.18$&$1520$\\
ESO-LTPV&$20$&$2198$&$209$\\
\hline
\end{tabular}
\end{table}