Session 31P. Comets II
Contributed Poster Session, Wednesday, October 14, 1998, 5:10-6:10pm, Hall of Ideas

## [31P.13] The Spatial Distribution of [O~I] in Comet Hale-Bopp from 2,000 to 1 \times 106~km

J. P. Morgenthaler, F. Scherb, C. W. Anderson, F. L. Roesler (UW--Madison), R. J. Oliversen (GSFC), N. E. Doane (Raytheon STX), W. H. Smyth (AER), M. L. Marconi (FPRI)

The exceptional brightness and long observational window of Comet Hale-Bopp provided a remarkable opportunity to study both the cometary neutral coma and the cometary plasma in the coma and ion tail. In response to this opportunity, a coordinated earth-based observing campaign for Comet Hale-Bopp was undertaken involving personnel from the University of Wisconsin and Goddard Space Fight Center. Seven different instruments were used to measure cometary emissions for H-\alpha, OH, O, H2O+, NH2, C, CN, C2, and the continuum. Here we present observations and model analysis for the [O~I]~6300~Å~emission line in Comet Hale-Bopp. In March 1997, the [O~I]~6300~Å~emission observations were recorded by four instruments on Kitt Peak. Two of the instruments were multi-object spectrographs (MOS) fed by the Wisconsin, Indiana, Yale, NRAO (WIYN) telescope. The third instrument was the 6 inch Fabry-Perot spectrometer that comprises the Wisconsin H\alpha Mapper (WHAM), which recorded narrow band images over a 1\circ field of view. The fourth instrument was a 2 inch Fabry-Perot spectrometer on the McMath-Pierce main telescope which recorded high resolution (\lambda/\Delta\lambda = 80,000) spectra of the [O~I]~6300~Å~line of the central 6~arcminutes of the comet. The combination of MOS and Fabry-Perot data covers spatial scales ranging from 2,000~km to 1 \times 106~km. The analysis conducted to date suggests that the [O~I] intensity as a function of radius resembles a function of the form A r-k(r) where k(r) varies from ~0.4 for r < 30,000~km, to ~2 for r > 200,000~km. Modeling analysis for the [O~I]~6300~Å~observations using the state-of-the-art Monte Carlo Particle Trajectory Model (MCPTM) of Combi and Smyth (Ap.J. 327, 1026-1043, 1988) including recent refinements (Combi {\it et. al.} Ap.J. 408, 668-677, 1993) will be discussed.