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Session 62 - Comet Hyakutake Encounter.
Display session, Wednesday, June 12
Comet Hyakutake (C/1996 B2) presented us with a very rare opportunity to study aspects of comets which are not normally observable. Since this comet was very active and passed only 0.1 AU from the Earth, it was ideal for studying near-nuclear phenomena. In particular, it was a perfect candidate for searching for parent molecules as at the time of closest approach the scale of the comet was only 75 km/arcsec. This meant we were able to observe the inner coma with a minimum of contamination from the outer regions.
We have obtained spectroscopy of the comet at millimeter wavelengths at the NRAO 12-meter dish and at visible/near UV wavelengths from the Lowell 72-inch.
Carbonyl Sulfide (OCS) was unambiguously detected for the first time in a comet (confirming a suggestion from the Vega IKS spectrometer experiment at P/Halley) with the NRAO 12-m on March 19, 1996 when the comet was at a geocentric distance of 0.218 AU. We also observed seven J(3-2) \DeltaK =0 transitions of methanol (CH_3OH) near 145 Ghz. A search for additional sulfur bearing molecules will be conducted from April 10 -12.
>From March 22 to 24 we conducted both a low (\sim10 Åand medium (\sim2 Åresolution line survey using the Lowell spectrometer. The low resolution spectra cover the spectral range of 3800 - 8400 Å\ and the medium resolution spectra include 3825 - 5015 ÅÅand 6235-6370 ÅP>We will present preliminary results of our observations, including detections of any low abundance species.
Program listing for Wednesday