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Arecibo Radar Image of Apophis
Delay-Doppler Arecibo radar image of Apophis Jan 28-29, 2005 from a distance of 0.192 AU. Although the best of the three radar opportunities, Apophis was at the limits of detection, thus barely imageable. Image from L. Benner (JPL).
Arecibo Radar Echoes From Apophis
Arecibo echo power spectra obtained during the three opportunities in 2005-2006. Solid and dashed lines show echo power in the opposite (OC) and same (SC) sense circular polarizations. Echo power in standard deviations of the noise is plotted as a function of Doppler frequency relative to the ephemeris predicted frequency for the asteroid's center of mass. The vertical scales are identical for each frame. The narrow bandwidth echo typical of a slowly rotating asteroid moved progressively closer to the central zero point with each successive radar experiment (top to bottom) as the ability to predict Apophis' motion improved. Figure by L. Benner (JPL).
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