\begin{table}%t1
\caption{\label{tab1}Timings of optical minima and \mbox{X-ray}/EUV dips of EK~UMa quoted as terrestrial time at the solar-system barycenter.}
%\centerline
 {\small \begin{tabular}{rccccrrrrcl} 
\hline \hline \noalign{\smallskip}
Cycle     & BJD(TT)        & \multicolumn{2}{c}{Error}  & $W$ & \multicolumn{2}{c}{$\rm O-C$} & \multicolumn{2}{c}{$\rm O-C-\Delta T_{\rm o,x}$}  & B & Instrument \\
number     & (days)         & (days)      & (phase)     &      & (days)      & (phase)     &   (days)    &  (phase)    &   &      \\
\noalign{\smallskip} \hline
\noalign{\smallskip}
$-137044 $&$ 43991.898920 $&$  0.001590 $&$  0.019989 $&$  0 $&$  0.002254 $&$  0.028331 $&$  0.000151 $&$  0.001894 $& X & {\it EINSTEIN}$^{~(1)}$\\  
$-106532 $&$ 46418.943640 $&$  0.003000 $&$  0.037715 $&$  1 $&$ -0.000242 $&$ -0.003038 $&$ -0.000242 $&$ -0.003038 $& O & Morris et~al.\\           
$ -84181 $&$ 48196.835820 $&$  0.001590 $&$  0.019989 $&$  0 $&$  0.003491 $&$  0.043886 $&$  0.001388 $&$  0.017449 $& X & {\it RASS}$^{~(2)}$\\      
$ -77149 $&$ 48756.187740 $&$  0.000350 $&$  0.004400 $&$  1 $&$  0.001844 $&$  0.023188 $&$ -0.000258 $&$ -0.003249 $& X & {\it ROSAT}\\             
$ -74652 $&$ 48954.809360 $&$  0.001590 $&$  0.019989 $&$  0 $&$  0.002040 $&$  0.025649 $&$ -0.000063 $&$ -0.000788 $& X & {\it ROSAT}$^{~(1)}$ \\    
$ -72610 $&$ 49117.238510 $&$  0.000350 $&$  0.004400 $&$  1 $&$  0.002296 $&$  0.028867 $&$  0.000193 $&$  0.002430 $& X & {\it ROSAT}\\             
$ -65258 $&$ 49702.046290 $&$  0.000500 $&$  0.006286 $&$  1 $&$  0.002423 $&$  0.030456 $&$  0.000320 $&$  0.004019 $& X & {\it EUVE}\\              
$ -46777 $&$ 51172.099370 $&$  0.000550 $&$  0.006914 $&$  1 $&$  0.002422 $&$  0.030453 $&$  0.000319 $&$  0.004016 $& X & {\it EUVE}\\              
$ -46359 $&$ 51205.348030 $&$  0.000580 $&$  0.007292 $&$  1 $&$  0.001681 $&$  0.021132 $&$ -0.000422 $&$ -0.005305 $& X & {\it EUVE}\\              
$ -45992 $&$ 51234.541220 $&$  0.000350 $&$  0.004400 $&$  1 $&$  0.002215 $&$  0.027842 $&$  0.000112 $&$  0.001405 $& X & {\it EUVE}\\              
$ -45673 $&$ 51259.915480 $&$  0.000350 $&$  0.004400 $&$  1 $&$  0.001931 $&$  0.024282 $&$ -0.000171 $&$ -0.002155 $& X & {\it EUVE}\\              
$ -45247 $&$ 51293.801400 $&$  0.000460 $&$  0.005783 $&$  1 $&$  0.002098 $&$  0.026374 $&$ -0.000005 $&$ -0.000063 $& X & {\it EUVE}\\              
$    -51 $&$ 54888.870790 $&$  0.000350 $&$  0.004400 $&$  1 $&$ -0.000154 $&$ -0.001938 $&$ -0.000154 $&$ -0.001938 $& O & {\it MONET/N}\\           
$     -1 $&$ 54892.847380 $&$  0.000690 $&$  0.008674 $&$  1 $&$ -0.000765 $&$ -0.009621 $&$ -0.000765 $&$ -0.009621 $& O & {\it MONET/N}\\           
$      0 $&$ 54892.927690 $&$  0.000350 $&$  0.004400 $&$  1 $&$  0.000001 $&$  0.000009 $&$  0.000001 $&$  0.000009 $& O & {\it MONET/N}\\           
$      1 $&$ 54893.007530 $&$  0.000350 $&$  0.004400 $&$  1 $&$  0.000297 $&$  0.003730 $&$  0.000297 $&$  0.003730 $& O & {\it MONET/N}\\           
$     24 $&$ 54894.836640 $&$  0.000350 $&$  0.004400 $&$  1 $&$ -0.000106 $&$ -0.001331 $&$ -0.000106 $&$ -0.001331 $& O & {\it MONET/N}\\           
$    200 $&$ 54908.836120 $&$  0.000350 $&$  0.004400 $&$  1 $&$ -0.000374 $&$ -0.004699 $&$ -0.000374 $&$ -0.004699 $& O & {\it MONET/N}\\           
$    201 $&$ 54908.916110 $&$  0.000350 $&$  0.004400 $&$  1 $&$  0.000072 $&$  0.000907 $&$  0.000072 $&$  0.000907 $& O & {\it MONET/N}\\           
$    275 $&$ 54914.803220 $&$  0.000690 $&$  0.008674 $&$  1 $&$  0.000925 $&$  0.011623 $&$  0.000925 $&$  0.011623 $& O & {\it MONET/N}\\           
$    276 $&$ 54914.882060 $&$  0.000350 $&$  0.004400 $&$  1 $&$  0.000220 $&$  0.002772 $&$  0.000220 $&$  0.002772 $& O & {\it MONET/N}\\           
$    277 $&$ 54914.961360 $&$  0.000350 $&$  0.004400 $&$  1 $&$ -0.000024 $&$ -0.000296 $&$ -0.000024 $&$ -0.000296 $& O & {\it MONET/N}\\           
$    564 $&$ 54937.790620 $&$  0.000350 $&$  0.004400 $&$  1 $&$  0.000102 $&$  0.001282 $&$  0.000102 $&$  0.001282 $& O & {\it MONET/N}\\           
$    565 $&$ 54937.870370 $&$  0.000350 $&$  0.004400 $&$  1 $&$  0.000308 $&$  0.003872 $&$  0.000308 $&$  0.003872 $& O & {\it MONET/N}\\           
$    576 $&$ 54938.744750 $&$  0.000350 $&$  0.004400 $&$  1 $&$ -0.000296 $&$ -0.003725 $&$ -0.000296 $&$ -0.003725 $& O & {\it MONET/N}\\           
$    577 $&$ 54938.824110 $&$  0.000690 $&$  0.008674 $&$  1 $&$ -0.000480 $&$ -0.006038 $&$ -0.000480 $&$ -0.006038 $& O & {\it MONET/N}\\           
$    615 $&$ 54941.847300 $&$  0.000350 $&$  0.004400 $&$  1 $&$  0.000037 $&$  0.000463 $&$  0.000037 $&$  0.000463 $& O & {\it MONET/N}\\           
 \hline 
\end{tabular}}
\medskip
$^{(1)}$~Based on the start of the bright phase at $\phi=-0.37\pm 0.02$ relative to the center of the \mbox{X-ray} dip. Not used in deriving the ephemeris;
$^{(2)}$~\rosat\ All Sky Survey. Not used in deriving the ephemeris. 
\end{table}