\begin{table}%t2
\caption{Log of the spectroscopic observations.
\protect\newline
This table is only available in electronic form at the CDS. It
contains the following information for 116~dates: Col.~1~--
number; 2~-- UT~date; 3~-- Julian date; 4~-- code according to Table~\ref{tab1}; 5~-- projected spectrograph entrance apertures; 6~-- wavelength
range covered; 7~-- spectral resolution; 8~-- mean seeing; 9~--
position angle~(PA) in degrees; \mbox{10~--~signal} to noise ratio in the
continuum (5160--5220)~\AA\ near H$\beta$ and (6940--7040)~\AA\ near H$\alpha$.}\label{tab2}
\end{table}