\begin{table}%t2
\caption{\label{t2}Telescopes and instrumentation.}
\small%\centerline
{
\begin{tabular}{rrr}
\hline\hline
Site        & NAO Rozhen                    & AO Belogradchik               \\
\hline
Telescope   & 2-m Ritchy-Chr\'etien         &  60-cm Cassegrain             \\
CCD type    & Photometrics AT200            &  ST8                          \\
Chip        & Site SI003AB UV-AR            &  KAF 1600                     \\
Chip size   & $1024\times1024$ pixels       &  $765\times510$ pixels$^{1}$  \\
Pixel size  & $24\times24$ $\mu$m           &  $18\times18$ $\mu$m$^{1}$    \\
Scale       & 0.31\arcsec/pixel             &  0.49\arcsec/pixel$^{1}$      \\
Field       & $5.3\arcmin\times5.3\arcmin$  &  $6.2\arcmin\times4.2\arcmin$ \\
Gain        & 4.93 e$^-$/ADU                &  2.3 e$^-$/ADU                \\
RON         & 1.03 ADU/rms                  &  10 ADU/rms                   \\
\hline
\end{tabular}}
\smallskip
$^{1}$ {With a binning factor of $2\times2$}.
\end{table}