We present a comprehensive photometric study of the old open cluster , NGC 6819 using 1 ^ { \circ } \times 1 ^ { \circ } field VI MOSAIC CCD imaging taken with the WIYN 0.9m telescope .
The resultant color-magnitude diagram ( CMD ) shows a well developed main sequence ( MS ) extending from V \sim 14.5 mag down to our photometric limit of V \sim 21 mag .
Fitting theoretical isochrones with adopted values of the reddening and metallicity ( E ( B - V ) = 0.14 , [ Fe / H ] = + 0.09 dex ) to the observed CMD yields a distance modulus of ( m - M ) _ { 0 } = 11.93 \pm 0.10 and an age of \sim 2.6 Gyr for NGC 6819 .
Our wide-field imaging reveals that NGC 6819 is larger in areal extent ( R = 13 ^ { \prime } ) than previously thought .
The wide-field also benefits our estimate of the degree of field star contamination , and ultimately yields improved measurements of the structural parameters ( r _ { c } = 2.80 ^ { \prime } , r _ { t } = 38.2 ^ { \prime } , and r _ { h } = 7 ^ { \prime } ) and tidal mass of the cluster ( M _ { tid } = 3542.4 M _ { \odot } ) .
The flattened luminosity and mass functions indicate that NGC 6819 has experienced mass segregation as a result of its dynamical evolution .
Our variability study of the cluster blue straggler star ( BSS ) population using the Welch-Stetson variability index ( I _ { WS } ) has revealed a number of variable BSS candidates .