A comparison of modeled and observed intensity profiles for C 2, C 3, CN, and the continuum for P/Halley

Intensity profiles were obtained for C 2, C 3, and CN emission and the continuum of P/Halley. The observations were made on 14 December 1985 and 6 and 8 January 1986, when the comet was between 0.90 and 1.28 AU from the Sun. Model intensity profiles were compared with the observations, and used to constrain the dust and gas parameters. Most of these parameters were consistent with expected values; however, the lifetimes of C 3 and its parent were much smaller than expected on each night, and the dust ejection velocity on 14 December was only 60% of the expected value. The day:night production rate ratio was found to be approximately 1:1 for the gas, and ranged from 4:3-1:0 for the dust.