Deep multicolor CCD photometry of the globular cluster NGC 6723

We have obtained CCD UBVRI photometry of 3620 stars in the globular cluster NGC 6723, one of the few globular clusters with a horizontal branch well-populated on both sides of the instability strip. This is the first deep five-color study of NGC 6723. We have determined several important parameters for this cluster. Its color excess is E(B-V) =0.11+/-0.01. The most plausible value of metallicity is [Fe/H]=-1.22+/-0.15; even lower values are possible. The apparent distance modulus of the cluster is (m-M)_{V,6723}=14.76. From isochrone analysis, we prefer the NGC 6723 age in the range between 15 and 16 Gyr, in the scale of Bergbusch & VandenBerg (1992). We find a close similarity of the shape and slope of the red giant branch in NGC 6723 and M 3 and of the magnitude difference between the main-sequence turnoff and the horizontal branch in NGC 6723, M 3, and M 5. Based on observations collected at the Las Campanas Observatory, Carnegie Institution of Washington.