MILLIMETER-WAVELENGTH SPECTROSCOPY OF CO, HCN, H2CO, AND CH3OH IN C 1996 B2 (HYAKUTAKE)/

Millimeter-wavelength spectra:were obtained of CO, HCN, H2CO, and CH3O H in comet C/1996 B2 (Hyakutake) with the NRAO 12 m telescope on Mar 2 1, 1996 UT. The emission of CO, H2CO, and HCN in the coma when the com et was similar to 0.16 AU from the Earth, providing a detailed look at the behavior of these species in the inner coma. The mapping data rev eal that line profiles, velocity offsets spatial profiles are not alik e for all four molecules. coma species shows properties of its own as if were not determined by their interaction with the water molecules. This preliminary report shows that excitation conditions are the most important factor in shaping the observed lines. Also presented are pro duction rates for these species near perigee. (C) 1997 Elsevier Scienc e Ltd.