title: List of exceptional asteroids
context: The largest asteroids with an accurately measured mass, due to the fact that they have been (and are being) studied by the probe Dawn, are 1 Ceres with a mass of 939.3 ± 0.5×1018 kg, and 4 Vesta at 259.076 ± 0.001×1018 kg. The third-largest asteroid with an accurately measured mass, due to the fact that it has moons, is 87 Sylvia at 14.78 ± 0.06×1018 kg.
question: What is the largest asteroid?
answers: 1 Ceres