The authors report in-situ observations of the number and energy densities of water-group (primarily O** plus , H//2O** plus ) ions derived from the measured distribution functions of these ions at distances ranging from approximately 4. 10**4 to approximately 4. 10**5 km from the comet. Our measurements were made with the Ultra Low Energy Charge Analyzer (ULECA) of the University of Maryland/Max-Planck-Institut experiment on the ICE spacecraft (Hovestadt et al. , 1978).