White dwarf stars in globular cluster NGC 6397

Image showing the very crowded sky field of the globular cluster NGC 6397, with some candidate White Dwarf stars indicated by red squares. This photo was obtained with the WPFC2 camera onboard the Hubble Space Telescope (HST). The image sharpness is about 0.1 arcsec and the "crosses" around the brighter stars are optical artifacts from the telescope optics. The field shown measures 1.3 x 1.3 arcmin 2.