Far-ultraviolet observations of the neutral comae of Comet Hale-Bopp (C/1995 01) near perihelion

The Ultraviolet Imager on the Polar spacecraft observed the neutral oxygen and carbon comae of Comet Hale-Bopp (C/1995 01) at far-ultraviolet waveleng ths near perihelion on March 31 and April 2, 1997. The OI (1304) coma was c ircularly symmetric with a diameter of about 5 million km. The coma was sma ller in the longer wavelength (1400-1600 Angstrom and 1600-1800 Angstrom) b ands, which is probably due to fluorescence of neutral carbon at 1561 Angst rom and 1657 Angstrom. The production rate for O calculated from the observ ed OI (1304) flux was (9.8 +/- 2.5) x 10(30). Using this value the estimate d production rate for OH was (8.9 +/-2.5) x 10(30) and for H2O was (1.0 +/- 0.3) x 10(31).