\begin{table}%t9
\caption {\label{tab3}Summary$^{{a}}$ of the optical properties of O-stars in NGC~2244 ({\it top part}) and Mon OB2 ({\it bottom}).}                  
%\centerline
 {          
\begin{tabular}{l c c c}   
\hline\hline          
Name & Spectral type & $v~\sin{i}$ & Spectroscopic status\\ 
\hline                    
  HD~46~056 & O8Vn  & 355$~\pm~$21 & C ? (rapid rotator)\\
  HD~46149 & O8V+B0--1V  & 78$~\pm~$11$^{\ddagger}$ & SB2\\
  HD~46~150 & O5.5V((f))  & 97$~\pm~$9 & Bin?\\
  HD~46~202 & O9V  & 54$~\pm~$15 & C\\
  HD~46~223 & O4V((f$^{+}$))  & 100$~\pm~$17 & C\\
  HD~46~485 & O8Vn  & 301$~\pm~$25 & C ? (rapid rotator)\\
\hline
  HD~46~573 & O7.5V((f)) & 110$~\pm~$18 & SB1\\
  HD~46~966 & O8.5V  & 63$~\pm~$17 & C\\
  HD~48~279 & ON7.5V  & 130$~\pm~$13 & C\\
\hline                  
\end{tabular} }
\par
\smallskip
\par
$^{{a}}$ The first column provides the name of each star studied in this paper. The next two columns give the spectral classification and the projected rotational velocity (in~km~s$^{-1}$) of the O-type stars, while the last column reports the status of the star as derived from our campaign: ``C'' means that our study did not reveal any indication of RV variability or of binarity, suggesting the star is probably single, ``Bin?'' indicates a potential binary, ``SB1'' corresponds to a spectroscopic binary where the second component has not been detected yet but where a period has been determined, whilst ``SB2'' corresponds to a spectroscopic binary where the two components are visible.
$^{\ddagger}$ Notes: the reported value for HD~46149 is the projected rotational velocity for the primary.
\end{table}