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We present analysis of deep CCD photometry for the very rich, old open starcluster NGC 6819. These CFH12K data results represent the first of nineteenopen star clusters which were imaged as a part of the CFHT Open Star ClusterSurvey. We find a tight, very rich, main-sequence and turn-off consisting ofover 2900 cluster stars in the V, B-V color-magnitude diagram (CMD).Main-sequence fitting of the un-evolved cluster stars with the Hyades starcluster yields a distance modulus of (m-M)v = 12.30 +/- 0.12, for a reddeningof E(B-V) = 0.10. These values are consistent with a newly calculatedtheoretical stellar isochrone of age 2.5 Gyrs, which we take to be the age ofthe cluster. Detailed star counts indicate a much larger cluster extent (R =9.5' +/- 1.0'), by a factor of ~2 over some previous estimates. Incompletenesstests confirm a slightly negatively sloped luminosity function extending tofaint (V ~ 23) magnitudes which is indicative of a dynamically evolved cluster.Further luminosity function and mass segregation tests indicate that low massobjects (M < 0.65Mo) predominate in the outer regions of the cluster, 3.5 < R <9.5. The estimation of the number of white dwarfs in NGC 6819 are in goodagreement with the observed number. For those white dwarf candidates which passboth a statistical and image classification tests, we show comparisons to whitedwarf isochrones and cooling models which suggest the need for spectroscopy toconfirm the white dwarf nature of the brighter objects.Comment: 15 Figures and 6 Tables available in higher resolution from ADS.  Accepted for Publication in AJ -- Kalirai et al. 2001b, 122, 266. Update

The CFHT Open Star Cluster Survey. II. Deep CCD Photometry of the Old Open Star Cluster NGC 6819