UPDATE October 12, 2017 (Benner et al. 2017):

Bistatic Goldstone DSS-13/Green Bank Telescope observations last night and
this morning have produced very strong echo power spectra and
delay-Doppler images with a range resolution of 1.9 meters/pixel. These
are the highest resolution delay-Doppler radar images ever obtained using
Goldstone transmissions. The images show an elongated object whose long
axis has a visible extent of at least 10 meters. The asteroid is so
small, though, that this resolution is placing only a modest number of
pixels on the object, so although we are seeing shape attributes, we
cannot see detail on the surface.

The echo power spectra have also shown a high circular polarization ratio
that is a) higher than we saw on Oct. 10 and b) consistent with results
seen from E- and V-class NEAs previously. The asteroid is much closer
Oct 11 than it was on Oct. 9 and 10 and the SNRs are orders of magnitude
stronger.

-Lance Benner