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Session 62 - Comet Hyakutake Encounter.
Display session, Wednesday, June 12
We report on the initial results from observations of comet C/1996 B2 (Hyakutake) using the imager on the WIYN 3.5m telescope at the Kitt Peak National Observatory. The WIYN imaging camera covers a field of 6.7' x 6.7' on a 2048 x 2048 CCD with 0.2" pixels ( 15 km/pixel at closest approach). Images were taken using filters to isolate dust continuum emission at 6830+/-36A and 4875+/-12A, neutral gas resonant lines of CN, C2, OH, and O, and ion emission features from H2O+ and CO+. This presentation focuses on the early analysis of gross morphological properties in the near nuclear region, and differences in the structure of the inner coma between images taken with different filters. We show the rotational behavior of the nucleus, and track the motion of several possible nuclear fragments using two series of images taken between 6:15-12:41 UT on March 26 and 10:15- 12:55 UT on March 27 with filters isolating the dust continuum, CN neutral, and H2O+ ion emissions. In addition we present images and a discussion of a conical structure extending behind the nucleus that is seen in images that isolate bright neutral gas emissions. The shape of the feature is most reminiscent of a 3-dimensional analog to a ship's wake, and is detectable as diffuse emission that emanates from near the nucleus with an 80-120 degreee opening angle and a single brightness enhancement along a partial arc at 2000km from the nucleus.
Program listing for Wednesday