This image was created from HST data from proposals 9815: I. King (University of Washington), J. Anderson (STScI), G. Piotto (University of Padova), and L. Bedin (STScI); and 10471: I. King (University of Washington), J. Anderson (STScI), G. Piotto (University of Padova), L. Bedin (STScI), S. Cassisi (Collurania Astronomical Observatory, Italy), and M. Salaris (Liverpool John Moores University).
The image is a composite of several separate exposures made by the ACS instrument on the Hubble Space Telescope. Two filters were used to sample broad wavelength ranges in the visible and near infrafed. The color results from assigning different hues (colors) to each monochromatic image. In this case, the assigned colors are: