\begin{table}%t2
\caption{\label{tb:observations}Summary of the new spectropolarimetry observations obtained with TBL/MuSiCoS.
 \object{HD~163472} or \object{V2052 Oph} (B2IV/V = 5.834 mag, $(B-V)$ = 0.05 mag, \Ebv\ $\sim$ 0.29 mag)
and \object{HD~174638} or \mbox{\object{* bet Lyr A}} (B7Ve, $V = 3.52$ mag, $(B-V)$ = 0.00 mag, \Ebv\ $\sim$ 0.135 mag)
are the two reddened lines of sight not previously studied in this context.
All spectra cover the wavelength range from 4480 to 6620~\AA.
$\tau_V/p_{\rm max}$ gives the ratio of the continuum optical depth over the continuum polarisation; see Eq.~(\ref{eq:2}).
For optimal alignment the maximum polarisation efficiency is $p_{\rm max} / \tau_V \sim\ 0.032$ 
or $\tau_V / p_{\rm max} \sim\ 31.25$ (\citealt{1975ApJ...196..261S}).
$S/N_{\rm I}$ is the signal-to-noise of the total transmittance spectrum at about 5800~\AA.
$^{(1)}$ PDLP is the 1$\sigma$ Polarisation Detection Limit per Pixel (1 pixel = 0.06~\AA), 
measured across  1~\AA\ at 5800~\AA. 
$^{(2)}$ PDLA is the 1$\sigma$ Polarisation Detection Limit per 0.8~\AA\ ($\approx$16~pixels), 
which is equal to the resolution obtained by \citet{1995ApJ...448L..49A}.}
\small%\begin{center}
{
\begin{tabular}{llllllllll}\hline\hline\noalign{\smallskip}
Targets		       & \Ebv & $A_V$		      & $\tau_V/p_{\rm max}$  & Stokes	& Date of observation	   & Exp. &$S/N_{\rm I}$ &PDLP$^{(1)}$ & PDLA$^{(2)}$ \\
Reddened:      	       & (mag)& (mag)		      &  	   &		   & 			   & (min)   &  	 & (\%)     &  (\%)	 \\\hline\noalign{\smallskip}
\object{HD~183143}     & 1.28 & 3.72$^1$	      &  58.2	   & $U, Q$	   & October 2004	   & 360     &   270	 & 0.4      &  0.12	 \\
        	       &      & 		      &  	   &		   & June 2004  	   & 540     &   400	 &$\sim$0.2 &   	 \\ 
\object{HD~197770}     & 0.58 & 1.61 $\pm$ 0.14$^2$  &  35.7	   & $U, Q$	   & October 2003	   & 360     &   528	 & 0.2      &  0.08	 \\
        	       &      & 		      &  	   &		   & June 2004  	   & 120     &   260	 &	    &		 \\ 
		       &      & 		      &  	   & $V$  	   & October 2003	   & 60      &   305	 & 0.9      &  0.3--0.7  \\
\object{HD~21291}      & 0.43 & 1.48$^1$	      &  41.5	   &$ U, Q$	   & October 2003	   & 360     &   1487	 & 0.06     &  0.04	 \\
\object{HD~198478}     & 0.54 & 1.48 $\pm$ 0.19$^2$  &  47.4	   & $U, Q$	   & June 2004  	   & 520     &   1160	 & 0.08     &  0.05	 \\ 
\object{HD~163472}     & 0.29 & 0.9$^3$	      &  	   & $V$  	   & June/July 2000, 2001, 2002	   & 1242    &   2000	 &$\sim$0.1 &  0.04	 \\ 
\object{HD~174638}     & 0.135& 0.4$^3$	      &  46.0	   & $U, Q$	   & June 2004  	   & 312     &   1500	 &	    &		 \\
Standard:              &      & 		      &  	   &		   &			   &	     &  	 &	    &		 \\
\object{HD~109387}     & 0.04 & 		      &  	   & $U, Q$	   & June 2004  	   & 232     &   1500	 &	    &		 \\
\hline 	
\end{tabular}}
\parbox{16.5cm}{
References: [1] \citet{2003ApJ...588..344D}; [2] \citet{2004ApJ...616..912V}; [3] average ISM value adopted: $R_V = 3.1$.} 
%\end{center}
\par
\end{table}