Arecibo Planetary Radar image of 1999
JM8 obtained 1999 Aug 5. 1999 JM8 is a slowly-rotating asteroid
that passed near the Earth in early August, 1999. It is several km
across, and was imaged at 15 m range resolution using the Arecibo
Planetary Radar system. The Doppler resolution is lower than the
range resolution, about 50 m, due to the slow rotation. In this
image, numerous craters and other surface features are visible.(More information on 1999 JM8)
Radar image of 2000 DP107, 2000 September. This figure
is an Arecibo radar image of the binary asteroid 2000 DP107,
showing the front cap of a roughly spherical primary and the
secondary orbiting at a distance of a few kilometers. Range from
the observer increases down and Doppler increases to the right.
The rotation of each object spreads the echo in Doppler frequency
and gives an exagerated ratio of sizes in that dimension. The
spin periods are less than three hours and more than a day for the
primary and secondary, respectively. The actual ratio of sizes,
measured from the range extents, is about 3 to 1. (Text by
Jean-Luc Margot, data from Margot et al.) (More information on 2000 DP107)
Radar image of 2000 UG11 obtained at Arecibo on 2000 Nov 7. Range
increases downward and Doppler shift increases towards the
right. Pixels are apporximately 15m square. The satellite is
clearly visible about 360 m farther (down in this image) from the
radar than the primary. The primary is apparently spherical, and
rotates in about 5 hours. 2000 UG11 is the smallest known binary
system, with a primary diameter of about 200m, and a separation of
about 400m.
This Arecibo Radar image of near-Earth
asteroid 1999 KW4 shows a sum of two hours of data obtained 2001 May
29. The range (vertical) resolution is 15 m, and the Doppler
(horizontal) resolution is about 5 m (on the primary). The secondary
is seen in front of the primary. The arcuate shape of the secondary
shows its motion about the primary over the two hour interval. Unlike
2000 DP107 and 2000 UG11, the primary of 1999 KW4 is not a spherical
object (though it is reasonably round). It clearly has large-scale
surface features, for example, there is some echo returned from past
the "terminator", which would be impossible for a perfectly spherical
target. (Image presented at the Asteroids 2001 Meeting in Palermo, Sicily).
Last modified 2001 June 26