We have been observing 1999 KW4 in 2001, 2002, 2017, and 2018. This asteroid is part of our long-term observing campaign for objects in highly elliptical orbits (Verma et al., 2017). We will observe it again in 2019 and 2020. This asteroid also happens to have been selected recently and independently as the target of the next International Asteroid Warning Network (IAWN) observing campaign.

Results shown below are available in our Science paper:

S. J. Ostro, J. L. Margot, L. A. M. Benner, J. D. Giorgini, D. J. Scheeres, E. G. Fahnestock, S. B. Broschart, J. Bellerose, M. C. Nolan, C. Magri, P. Pravec, P. Scheirich, R. Rose, R. F. Jurgens, E. M. De Jong, S. Suzuki. Radar Imaging of Binary Near-Earth Asteroid (66391) 1999 KW4. Science 314, 1276-1280, 2006.

The data below were acquired on 2001 May 26-29 with our custom-built Portable Fast Sampler and yield images at 15 m resolution.

The sequence of radar images can be inverted to yield a 3D model of each component. The image below shows the primary.

The radar data provide an exquisite characterization of the binary system, with measurement precisions approaching that obtainable from spacecraft.