\begin{table}%t2
\caption{\label{stars_mag}Positional and photometric data for spectroscopically observed stars in Mercer~23.}
%\centerline
{\small
\begin{tabular}{lllrlrlrrclll}
\hline\hline
\multicolumn{1}{l}{Object} &
\multicolumn{1}{c}{RA(J2000)} &
\multicolumn{1}{c}{Dec(J2000)} &
\multicolumn{1}{c}{$J$} &
\multicolumn{1}{c}{Err~$J$} &
\multicolumn{1}{c}{$H$} &
\multicolumn{1}{c}{Err~$H$} &
\multicolumn{1}{c}{$K_{\rm S}$} &
\multicolumn{1}{c}{Err~$K_{\rm S}$} &
\multicolumn{1}{c}{Magnitude} &
\multicolumn{1}{c}{Spectral}&  
\multicolumn{1}{c}{RV} &
\multicolumn{1}{c}{Err~RV}  \\
\multicolumn{1}{l}{} &
\multicolumn{1}{c}{deg} &
\multicolumn{1}{c}{deg} &
\multicolumn{1}{c}{mag} &
\multicolumn{1}{c}{mag} &
\multicolumn{1}{c}{mag} &
\multicolumn{1}{c}{mag} &
\multicolumn{1}{c}{mag} &
\multicolumn{1}{c}{mag} &
\multicolumn{1}{c}{Source} &
\multicolumn{1}{c}{type} &
\multicolumn{1}{c}{km~s$^{-1}$} &
\multicolumn{1}{c}{}  \\
\hline
Obj1$^\star$ & 292.557583 & 18.533426 & 10.615 & 0.033 &  9.834 & 0.032 &  9.524 & 0.041 & 2MASS & O5.5I&-- & --  \\
Obj2 & 292.556499 & 18.534004 &  8.646 & 0.021 &  7.835 & 0.017 &  7.332 & 0.020 & 2MASS & WR &-- &  -- \\
Obj3 & 292.553464 & 18.536149 & 13.853 & 0.021 & 13.062 & 0.019 & 12.700 & 0.021 & PANIC & O9/B2 &86&2  \\
Obj4 & 292.547841 & 18.539963 & 13.168 & 0.025 & 12.382 & 0.020 & 12.019 & 0.020 & PANIC & O9/B2&67&4 \\
Obj5 & 292.556914 & 18.539985 & 15.379 & 0.020 & 14.478 & 0.021 & 14.117 & 0.019 & PANIC & B &88&10    \\
Obj6 & 292.555502 & 18.538446 & 10.199 & 0.026 &  9.420 & 0.029 &  9.033 & 0.024 & 2MASS & O6If &-- & --\\
Obj7 & 292.554421 & 18.537366 & 14.688 & 0.021 & 13.834 & 0.021 & 13.452 & 0.022 & PANIC & B  &83&11 \\
Obj8 & 292.552262 & 18.535301 & 10.875 & 0.025 & 10.126 & 0.027 &  9.861 & 0.022 & 2MASS & field &-- &--\\
Obj9 & 292.553299 & 18.532497 & 13.932 & 0.023 & 13.063 & 0.022 & 12.700 & 0.020 & PANIC & O9/B2 &67& 12 \\
Obj10 & 292.552102 & 18.531113 & 13.193 & 0.021 & 12.338 & 0.019 & 11.975 & 0.020 & PANIC & O9/B2&80&8 \\ 
Obj11 & 292.554488 & 18.533974 & 13.043 & 0.019 & 12.223 & 0.019 & 11.854 & 0.020 & PANIC & O9/B2&91&9 \\
\hline
\end{tabular}}
\tablefoot{The magnitudes of the brightest stars, saturated on PANIC images, are taken from 2MASS. The magnitudes of Obj1, noted with asterisk, are obtained by us from PSF photometry on 2MASS images.}
\end{table}