Question: What is the km of the solar system body that was observed by Arecibo radar in April 2008 ?

text: List of Solar System objects by size
List of objects by radius -- From 50 to 99 km

This is a partial list of Solar System objects by size, arranged in descending order of mean volumetric radius, and divided into several size classes. These lists can also be sorted according to an object's mass and, for the largest objects, volume, density and surface gravity, insofar as these values are available. This list contains the Sun, the planets, dwarf planets, many of the larger small Solar System bodies (which includes the asteroids), all named natural satellites, and a number of smaller objects of historical or scientific interest, such as comets and near-Earth objects. Objects on this list are ordered by mean radius rather than mass; thus, objects on the lower portions of the table can be more massive than objects higher on the list if they have a higher density. Many trans-Neptunian objects (TNOs) have been discovered; in many cases their positions in this list are approximate, as there is frequently a large uncertainty in their estimated diameters. Solar System objects more massive than 1021 kilograms (one yottagram [Yg]) are known or expected to be approximately spherical. Astronomical bodies relax into rounded shapes (ellipsoids), achieving hydrostatic equilibrium, when their own gravity is sufficient to overcome the structural strength of their material. It was believed that the cutoff for round objects is somewhere between 100 km and 200 km in radius if they have a large amount of ice in their makeup; however, later studies revealed that icy satellites as large as Iapetus (1,470 kilometers in diameter) are not in hydrostatic equilibrium at this time, and a 2019 assessment suggests that many TNOs in the size range of 400-1000 kilometers may not even be fully solid bodies, much less gravitationally rounded. Objects that are ellipsoids due to their own gravity are here generally referred to as being round, whether or not they are actually in equilibrium today, while objects that are clearly not ellipsoidal are referred to as being irregular. Spheroidal bodies typically have some polar flattening due to the centrifugal force from their rotation, and can sometimes even have quite different equatorial diameters (scalene ellipsoids such as Haumea). Unlike bodies such as Haumea, the irregular bodies have a significantly non-ellipsoidal profile, often with sharp edges. There can be difficulty in determining the diameter (within a factor of about 2) for typical objects beyond Saturn.
Body Radius ( km ) Mass ( 10 kg ) Type - notes Refs r · M
Chicago 334 99.4 ± 2.8 5.1 ± 5.6 belt asteroid type C ·
Bienor 54598 99 +3 −3.5  centaur · M
Themis 24 98 ± 2 5.9 ± 1.9 belt asteroid type C ; Themis family ·
Larissa Neptune VII 97 ± 5 ≈ 4.2 moon of Neptune ·
Ursula 375 96.8 ± 1.3 8.4 ± 5.3 belt asteroid type C ·
S/2002 ( 2001 QC 298 ) 1 2001 QC 298 I 96 +9 −10  secondary of 2001 QC 298 · M
S/2018 ( 532037 ) 1 2013 FY 27 I ≈ 95  moon of ( 532037 ) 2013 FY 27 · M
Amphitrite 29 94.8 ± 0.6 13 ± 2 belt asteroid type S ·
Daphne 41 94.5 ± 0.5 6.3 ± 0.1 belt asteroid type C ; binary ·
Aurora 94 93.8 ± 3.6 6.2 ± 3.6 belt asteroid type C ·
Hermione 121 94 ± 3 5.0 ± 0.3 outer belt asteroid type C ; binary ·
Bertha 154 93.4 ± 0.9 9.2 ± 5.2 belt asteroid type C ·
Hebe 6 92.6 ± 1.4 14 ± 1 belt asteroid type S ·
Metis 9 ≈ 92 8.4 ± 1.7 belt asteroid type S ·
Elektra 130 90.3 ± 1.3 6.6 ± 0.4 belt asteroid type G ; trinary ·
Loreley 165 90 ± 1 ≈ 19 ± 2 belt asteroid type C ·
Janus Saturn X 89.5 ± 1.4 1.898 ± 0.001 moon of Saturn ·
Teharonhiawako 88611 89 +16 −18 2.44 ± 0.03 cubewano ; binary ·
Nemesis 128 89 ± 1 6.0 ± 2.6 belt asteroid type C ·
Aegle 96 88.9 ± 0.8 6.4 ± 6.3 belt asteroid type T ·