\begin{table}%T1
 \caption{Basic and derived data for observed targets. Magnitudes and colours
 are taken from the 2MASS database, except for IRAS~17175--3544 by Tapia et~al. (1996).}
 \label{tab1}
 %\centerline
 {
 \begin{tabular}{lllllll}\hline\hline
 IRAS & $H$ &  $J-H$ & $H-K$ & $A_{\rm v}$ & Sp.T. & Int./s \\ \hline
 17175--3544$^a$ & 14.00 & 2.75 & 3.43 & $>$13$^d$  & O6-O7& 7560 \\ 
 17441--2910$^b$ & 10.29 & 3.42 & 2.41 & 30 & O5.5 & 480 \\ 
 18079--1756$^c$ & 11.09 & 2.67 & 1.67 & 74 & B    & 960 \\  \hline
 \end{tabular}
}\smallskip
$^a$ Walsh et~al. (1999). \\
$^b$ Porter et~al. (1998), \cite{wal97}. \\ 
$^c$ Osterloh et~al. (1997). \\ 
$^d$ Using the given spectral type and using a distance of 2.2~kpc (see text) we derive $m_{\rm v}=6$, yet
there is no optical counterpart on DSS plates.
\end{table}