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C. Dreier (Oberlin College), C. Magri (University of Maine, Farmington), E. Howell, M. Nolan (Arecibo Observatory)
The near-Earth asteroid (7753) 1988 XB made a close approach to Earth during the Fall of 2004. Each Day during the period of November 22nd through the 26th, the Arecibo Observatory Planetary Radar made continuous wave and delay-Doppler imaging measurements at 7.5 meter resolution. Immediately apparent from the delay-Doppler maps was that 1988 XB is an irregularly-shaped object with a relatively slow rotation period. The data are consistent with principal axis rotation with a period of (19.9 ± 0.1) hours. The apparent diameter varied between 1.3 and 2.0 km, which reflects the elongated shape of the object. We used Hudson's (1993) "Shape" software to form a plausible physical model of the asteroid. The properties mentioned above were used with the 1-D and 2-D radar data to define a starting model. Preliminary results show a large outcropping of rock which defines 1988 XB's irregular radar echo. Multiple starting conditions were used to test the uniqueness of this solution. Other preliminary results suggest a sub-radar latitude of approximately 60 degrees and a major-axis diameter of (1.7 ± 0.2) km, which are consistent with initial measurements. Further results will be presented.
The Arecibo Observatory is operated by Cornell University under a cooperative agreement with the National Science Foundatation.
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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.