Color-magnitude diagrams for three distant globular clusters

J. G. Cohen
1985 Astronomical Journal  
Color-magnitude diagrams are presented for three distant galactic globular clusters (NGC 5466, NGC 6229, and NGC 7006). In each case the photometry reaches below the main-sequence turnoff; the ages deduced by comparison with stellar evolutionary isochrones are indistinguishable from those of the well-studied nearby clusters. The luminosity functions derived from computer-generated star counts complete to a well-defined limiting magnitude in selected fields support identical ages for the three
more » ... usters with maximum differences between NGC 5466 and NGC 6229 of 10% of the age, and between NGC 5466 and NGC 7006 of 25%. The previously published claims of an exceptionally bright turnoff for NGC 7006 are shown to be spurious. The horizontal branch of NGC 6629 is unusually red for its metallicity. Star counts and tidal radii are discussed for NGC 6229 and NGC 7006.
doi:10.1086/113929 fatcat:rjoa5fbg4vhbnmwf7enukagjem