\begin{table}%t2
\caption{\label{tab:colours}Observed and calculated photometric parameters of HD~49933.}
%\centerline
 {
\small 
\begin{tabular}{cccccc}
\hline\hline
Colour   & \textbf{SIMBAD}   & t6500g4.0 & t6500g3.85  & t6550g4.25 & t6780g4.24 \\
index           &                   & (Model~1) & (Model~2)   & (Model~3)  & (Model~4) \\
\hline
$b-y$         &$\mathbf{0.270}$   &$0.2754$   &$0.2727$	  &$0.2724$    &$0.2399$     \\  
                & ($0.002$) &&&\\
$m_{\rm 1}$     &$\mathbf{0.127}$   &$0.1251$   &$0.1255$	  &$0.1330$    &$0.1355$     \\  
                & ($0.004$) &&&\\
$c_{\rm 1}$     &$\mathbf{0.460}$   &$0.5123$   &$0.5502$	  &$0.4400$    &$0.5126$     \\  
                & ($0.003$) &&&\\
$H\beta$        &$\mathbf{2.662}$   &$2.7272$   &$2.7291$	  &$2.7279$    &$2.7501$     \\  
$B-V$         &$\mathbf{0.390}$   &$0.3865$   &$0.3829$	  &$0.3865$    &$0.3371$     \\    
$U-B$         &$\mathbf{-0.070}$  &$-0.0628$  &$-0.0457$	  &$-0.0942$   &$-0.0882$   \\ \\
\textbf{Geneva} &&&&\\
$U-B$         &$\mathbf{1.235}$   &$1.2561$   &$1.2896$	  &$1.1950$    &$1.2285$     \\  
$V-B$         &$\mathbf{0.491}$   &$0.5125$   &$0.5166$	  &$0.5123$    &$0.5700$     \\  
$B_{\rm 1}-B$  &$\mathbf{0.973}$   &$0.9842$   &$0.9835$	  &$0.9878$    &$0.9723$     \\  
$B_{\rm 2}-B$  &$\mathbf{1.391}$   &$1.4142$   &$1.4152$	  &$1.4102$    &$1.4252$     \\  
$V_{\rm1}-B$  &$\mathbf{1.224}$   &$1.2423$   &$1.2461$	  &$1.2420$    &$1.2962$     \\  
$G-B$         &$\mathbf{1.586}$   &$1.6135$   &$1.6185$	  &$1.6146$    &$1.6847$     \\  
\hline                                                              
\end{tabular}}
\medskip
The values in brackets give the error bars of observations.
\end{table}