\begin{table}%t2
\caption{Emission measures and \ha luminosities.\label{tab2}}
%\centerline
 {\begin{tabular}{cccccc}
\hline
\hline
Object & Date &  Ref. &$EM_{\rm obs}$& $L_{\alpha}$(0)& $L_{\alpha}$(200) \\
       &      &       & [cm$^{-3}$]  &  [$L_{\odot}$]  &    [$L_{\odot}$]   \\
\hline
   \multicolumn{6}{c}{Quiescent phases}             \\
Z~And     & 30/06/86 & 1, 2 & 8.8E+59  &  9.8 & 1.83\\ 
           & 07/07/87 & 1, 2 & 5.7E+59  &  7.6 & 0.99\\ 
           & 22/09/88 & 1, 2 & 3.8E+59  &  5.1 & 0.87\\ 
AX~Per    & 01/11/93 &  3  & 1.7E+59  &  6.6 & 1.20\\
RW~Hya    & 10/07/92 & 1, 2 & 9.2E+58  &  1.1 & 0.34\\ 
SY~Mus    & 14/07/88 & 1, 2 & 3.6E+59  &  3.0 & 0.14\\ 
CI~Cyg    & 21/09/88 & 1, 2 & 7.5E+59  &  8.0 & 0.40\\ 
           & 20/06/89 & 1, 2 & 4.8E+59  &  3.3 & 0.48\\ 
V1329~Cyg & 21/09/88 & 1, 2 & 2.1E+60  & 12.5 & 1.60\\ 
           & 16/09/89 & 1, 2 & 4.8E+59  &  7.1 & 1.20\\
           & 30/06/86 & 1, 2 & 1.5E+60  &  6.2 & 1.36\\
           & 06/05/90 & 1, 2 & 1.3E+60  &  6.1 & 1.11\\
           & 29/07/91 & 1, 2 & 1.7E+60  &  8.7 & 1.68\\
BF~Cyg    & 20/08/94 & 1, 2 & 4.0E+60  & 12.6 & 1.86\\
V443~Her  & 20/06/89 & 1, 2 & 1.6E+59  &  3.3 & 0.53\\
           & 04/05/90 & 1, 2 & 3.4E+59  &  2.6 & 0.23\\
AG~Peg    & 15/07/88 & 1, 2 & 4.8E+59  &  4.6 & 0.68\\
           & 07/07/87 & 1, 2 & 4.3E+59  &  2.5 & 0.54\\
AG~Dra    & 18/06/86 & 1, 2 & 1.4E+59  &  2.8 & 0.86\\
   \multicolumn{6}{c}{Active phases}                \\
Z~And     & 11/12/00 &  4  & 2.1E+60  & 20.8 & 5.50\\
           & 02/02/03 &  4  & 2.6E+60  & 28.7 & 8.56\\
           & 31/07/03 &  4  & 1.3E+60  & 25.1 & 4.59\\
           & 13/11/03 &  4  & 1.0E+60  & 22.1 & 3.76\\
AR~Pav    & 14/07/88 & 1, 2 & 1.7E+60  & 39.5 & 9.20\\
AE~Ara    & 14/07/88 & 1, 2 & 5.3E+59  & 36.4 & 6.30\\
BF~Cyg    & 04/06/93 &  5  & 2.8E+60  & 62.7 & 6.20\\
           & 21/09/88 & 1, 2 & 4.1E+60  & 33.8 & 6.10\\
AX~Per    & 22/09/88 & 1, 2 & 3.6E+59  &  7.1 & 2.00\\ 
PU~Vul    & 28/09/88 & 1, 2 & 1.0E+61  & 144  & 9.50$^\dagger$\\
\hline                                              
\end{tabular}}
\par
\smallskip
Ref.: 1 -- \cite{vw+93}; 2 -- \cite{i+94};
      3 -- \cite{sk+01}; 4 -- \cite{sk+06}; 
      5 -- \cite{sk+97}.\\
$^\dagger$ = $L_{\alpha}$(500).
\end{table}