**Table 1:** Transformation between g'-r' and $V-R _{\rm C}$ .
$\begin{displaymath}\begin{tabular}{rcl} \hline\hline $V$& =& $g' - 0.55(g'-r') ... ...{\rm C} $ & =&$ -0.14g' + 1.14r' +0.14$\\ \hline \end{tabular}\end{displaymath}$

	1 Introduction
	2 Observations, data reduction and photometry
	3 Results
	4 Summary
	References