McDonald Observatory Spectral Observations of Comet 19P/Borrelly

Abstract

We report on spectroscopic observations of the Deep Space 1 comet target, 19P/Borrelly. These observations were obtained during 1981, 1987, and 1994 at McDonald Observatory. We compute column densities for eight bands at a variety of positions within the coma and use these data and a Haser model in order to derive production rates for the gas. With these production rates, we show that Borrelly is a member of the carbon-chain molecule “depleted” class of comets. We also derive a measure of the dust in the coma ( Afρ) and show that this is a moderately dusty comet. We see, for the first time, a hint that the ratio C 3 and CH to CN production may vary with heliocentric distance.