\begin{table}%[!]%t4
\caption{$R_{\rm V}$ values derived from optical and infrared photometry based on three different methods.
The one but last column lists previously reported values for $R_{\rm V}$.
In Col.~2 we list the comparison stars (or spectral type) adopted to compute $R_{\rm V}$ for the 
targets in Col.~1 as discussed in the main text.
Together with the reddening (Col.~3) three methods were used to derive $R_{\rm V}$ (Cols.~5--7).
The average $R_{\rm V}$ is given in Col.~8, and a literature value is given in Col.~9 when available.
The last Col.~10 gives the spectral type of the adopted comparison target 
or the foreground reddening based on the Galactic extinction curve ($R_{\rm V} = 3.1$) that is subtracted from 
the constructed "total'' extinction curve.\label{tb:Rv}}
%\vspace*{-1.5mm}
%\centerline
$$
 {\begin{tabular}{lllllllrlll}\hline\hline
				&				&		 & \multicolumn{3}{c}{$R_{\rm V}$ from {\it JHK}}& &											& $R_{\rm V}$ from		& \\
Target				& Comparison   	     		& \Ebv\ $^{[a]}$ & G03   & F99   & CCM89 & average $^{[b]}$ &	 										& literature       		&  Notes  \\ \hline
%				& \object{Sk -70 120} $^{[5]}$	& 0.170       	 & 4.43  & 4.54  & 4.65  & 4.54 (0.15)	&											 &				  &  B1.5~Ia		   \\	   
{Sk --69 223}  $^{[5]}$	& {Sk --67 5}   $^{[5]}$	& 0.230	         & 3.49  & 3.50	 & 3.55  & 3.51 (0.05)  & \multirow{4}*{\resizebox{4mm}{11mm}{\Large \} } } \multirow{4}*[0mm]{3.63 (0.15)	 }									  &				  &  B0~Ia		   \\	
			   	& B1.5~Ia $^{[1]}$	  	& 0.210	       	 & 3.69	 & 3.72  & 3.79  & 3.73 (0.07)	&											 &				  & \Ebv$_{\rm,MW}$ = 0.07 \\
				& B1.0~Ia $^{[1]}$  		& 0.230	       	 & 3.62	 & 3.64  & 3.71  & 3.66 (0.07)	&											 &				  & \Ebv$_{\rm,MW} = 0.07$ \\
%				& B0.5~Ia $^{[1]}$  		& 0.240	       	 & 3.63	 & 3.65  & 3.71  & 3.66 (0.06)	&											 &				  & \Ebv$_{\rm,MW}$ = 0.07 \\
				& B0~Ia   $^{[1]}$  		& 0.260	       	 & 3.61	 & 3.62  & 3.67  & 3.63 (0.05)	&											 &				  & \Ebv$_{\rm,MW} = 0.07$ \\
%				& O9~Ia   $^{[1]}$		& 0.310		 & 3.54  & 3.55  & 3.60  & 3.56 (0.04)  &											 &				  & \Ebv$_{\rm,MW}$ = 0.07 \\
				& {Sk~--65 15} $^{[5]}$	& 0.210 	 & 3.92  & 3.90  & 3.94  & 3.92 (0.02)  & \multirow{3}*{\resizebox{4mm}{8mm}{\Large \} } } \multirow{3}*[0mm]{4.01 (0.05)}	 &				 &  O...  \\   
				& {Sk~--65 19} $^{[5]}$	& 0.190 	 & 4.07  & 4.06  & 4.11  & 4.08 (0.04)  &											 &				 &  O...  \\	  
				& {Sk~--65 41} $^{[5]}$ 	& 0.190  	 & 4.02  & 4.01  & 4.05  & 4.03 (0.03)  &											 &				 &  O...  \\	   
%				& {Sk -65 56} $^{[5]}$	& 0.260  	 & 4.16  & 4.17  & 4.24  & 4.19 (0.06)  &											 &				 &  O...  \\
{Sk~--69 243} $^{[5]}$	& {Sk --66 28} $^{[5]}$ 	& 0.280		 & 5.79  & 5.79  & 5.88  & 5.82 (0.08)  &											 & \multirow{2}*[0mm]{3.7 $^{[6]}$, 3.5 $^{[7]}$}		 & WR	 \\
				& {Sk~--67 18} $^{[5]}$	& 0.350	    	 & 2.45  & 2.72  & 2.83  & 2.67 (0.28)  &											 &				 & WN/WR \\	 
{Sk~--67 2} $^{[5]}$ 	& {Sk~--66 35} $^{[5]}$ 	& 0.150	     	 & 3.69  & 3.69  & 3.69  & 3.69 (0.01)  & 3.69 (0.01)											 & $3.62\pm0.35$ $^{[3]}$	 & B1.5~Ia\\
			   	& B1.5~Ia $^{[1]}$	  	& 0.136		 & 3.73  & 3.74  & 3.81  &  3.76 (0.06) & \multirow{3}*{\resizebox{4mm}{8mm}{\Large \} } } \multirow{3}*[0mm]{3.64 (0.29)}	 &				 & \Ebv$_{\rm,MW}$ = 0.114 \\
				& B2~Ia   $^{[1]}$	 	& 0.126		 & 3.71  & 3.75  & 3.82  & 3.76 (0.07)  &											 &				 & \Ebv$_{\rm,MW}$ = 0.114 \\
			     	& B2~I    $^{[2]}$ 	    	& 0.146 	 & 3.38  & 3.38  & 3.43  & 3.40 (0.2)	&											 &				 & \Ebv$_{\rm,MW}$ = 0.114\\
{Sk~--68 135}  $^{[5]}$	& B0~Ia   $^{[1]}$		& 0.220		 & 3.96  & 3.94  & 3.98  & 3.96 (0.03)  & 3.96 (0.03)										 & 4.05 $^{[4]}$		 & \Ebv$_{\rm,MW}$ = 0 \\
				& B0~Ia   $^{[1]}$    		& 0.130		 & 4.49  & 4.48  & 4.54  & 4.50 (0.05)  & \multirow{3}*{\resizebox{4mm}{8mm}{\Large \} } } \multirow{3}*[0mm]{4.49 (0.09)}	 &				 & \Ebv$_{\rm,MW}$ = 0.09 \\
				& B0.5~Ia $^{[1]}$  		& 0.110		 & 4.70  & 4.70  & 4.77  & 4.72 (0.06)  &											 &				 & \Ebv$_{\rm,MW}$ = 0.09 \\
				& {Sk~--67 5} $^{[5]}$ 	& 0.120		 & 4.24  & 4.25  & 4.29  & 4.26 (0.04)  &											 &				 & B0~Ia	 \\
\hline
\end{tabular}		                   
}$$
\par
\smallskip
References: Intrinsic infrared colours from: 
		               $^{[1]}$ \citet{1994MNRAS.270..229W}; 
		               $^{[2]}$ \citet{1966CoLPL...4...99J}. 
		               $^{[3]}$ \citet{2003ApJ...594..279G}; 
		               $^{[4]}$ \citet{1982MNRAS.199..979M}; 
		               $^{[5]}$ 2MASS \citep{2003yCat.2246....0C}; 
		               $^{[6]}$ \citet{1983ApJ...265..194C}; 
		               $^{[7]}$ \citet{1984IAUS..108..255S}. \\%
$^{[a]}$ Colour excess derived by adopting intrinsic colours for 
supergiants from \citet{1994MNRAS.270..229W}, \citet{1982BICDS..23....2S}, 
	  \citet{1966CoLPL...4...99J};
$^{[b]}$~Errors in average $R_{\rm V}$ column are based on sigma from average 
of the methods G03 (\citealt{2003ApJ...594..279G}), F99 (\citealt{1999PASP..111...63F}) and 
CCM89 (\citealt{1989ApJ...345..245C}), plus the typical error on $R_{\rm V}$ resulting from a 
0.5~spectral type mismatch (assuming same luminosity class). 
\end{table}