DPS Meeting, Madison, October 1998
Session 42P. Comets IV
Contributed Poster Session, Wednesday, October 14, 1998, 5:10-6:10pm, Hall of Ideas

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[42P.12] McDonald Observatory Spectroscopic Observations of Comet 19P/Borrelly

A. L. Cochran (U. Texas)

Recent changes in the launch date for the {\it Deep Space 1\/} mission have necessitated changing the cometary target to comet 19P/Borrelly. We have obtained moderate resolution spectroscopic observations of Borrelly during three apparitions at McDonald Observatory: 1981, 1987, 1994. For the first two of these apparitions, observations were obtained at 11.5Å\ resolution in the spectral range 3500--6500Å\ using an Intensified Dissector Scanner Spectrograph (IDS). For the last apparition, the observations were obtained with the Large Cassegrain Spectrograph (LCS), a long slit CCD spectrograph, covering the spectral range 3000--5700Å\ at 7Å\ resolution. In all apparitions, spectra were obtained at a variety of cometocentric distances. In 1981, we observed on five nights covering heliocentric distances from 1.44 to 1.32 preperihelion; in 1987, we observed on 10 nights covering heliocentric distances of 1.65 to 1.40 preperihelion and 1.36 to 1.70 postperihelion; in 1994, we observed on 8 nights covering heliocentric distances of 1.40 preperihelion and 1.37 to 1.42 postperihelion.

The IDS was used to observe emission bands of CN, C3, CH, NH2 and C2 (\Delta v = 1 and 0 bands). The LCS was used to observe emission bands of OH, NH, CN, C3, CH, and C2 (\Delta v = 1 and 0 bands). In addition, we have measured the dust parameter Af\rho. In this paper, we present the three data sets, detailing the distribution of gas with cometocentric distance and the evolution of the gas with time. We will also compare our results with those of others.

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