CCD photometry of the distant southern globular cluster NGC 5824

Abstract

A V, (B-V) C-M diagram for the distant globular cluster NGC 5824 is obtained from CCD observations of 285 stars reaching V = 20.5. Assuming a reddening of E(B-V) = 0.13, the color of the giant branch at the level of the horizontal branch is found to be (B-V)o,g = 0.77, while the apparent distance modulus (V-Mv) is shown to be 18.0 + or - 0.2. Also, an Fe/H abundance ratio = -1.7 and a heliocentric distance of 33 + or - 3 kpc are estimated. The results produce a galactocentric distance of 25 kpc. This result is combined with the radial-velocity determination of Hesser, Shawl, and Meyer (1986), making it possible to plot the representative point of the cluster in Lynden and Bell's (1983) velocity-distance diagram.