Radar astrometry provides measurements related to a body's position and/or velocity.
Radar "delay" measurements provide range between the observer and the body
while "Doppler" measurements provide range-rate between the observer and the body.
Since typical optical astrometry provides measurements of a body's position
in the plane-of-sky (normally RA and Dec.), the addition of radar astrometry
provides very valuably out-of--plane measurements, typically resulting in
significant improvements in the accuracy of orbit determination,
especially for small-bodies.
Radar is not only useful in improving the accuracy of a small-body's orbit,
but is also a very powerful means of determining physical characteristics
of a small-body such as shape, surface roughness, and rotational state.
Please visit JPL's
Asteroid Radar Research
site for more information and related data.
Radar astrometry data are available for some planets and a few small-bodies,
as described below.
Radar astrometry for some of the planets is available from
Asteroids and Comets
Radar Astrometry Data
Last updated: 2014-Aug-18
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