We continue our series of papers describing the results of a photometric survey of open star clusters , primarily in the southern hemisphere , taken in the u ^ { \prime } g ^ { \prime } r ^ { \prime } i ^ { \prime } z ^ { \prime } filter system .
The entire observed sample covered more than 100 clusters , but here we present data only on NGC 188 , which is one of the oldest open clusters known in the Milky Way .
We fit the Padova theoretical isochrones to our data .
Assuming a solar metallicity for NGC 188 , we find a distance of 1700 \pm 100 pc , an age of 7.5 \pm 0.7 Gyr , and a reddening E ( B - V ) of 0.025 \pm 0.005 .
This yields a distance modulus of 11.23 \pm 0.14 .