Asteroid 1989 PB was discovered on August 9, 1989, by
Eleanor Helin
on photographic plates taken on Palomar
Observatory's 18-inch Schmidt telescope.
The slightly elongated smudge near the center of this image is the asteroid. |
Two days later, orbital calculations showed that this object was approaching the Earth and would pass within the Arecibo Observatory's field of view during August 19-22 at distances likely to provide echoes much stronger than in previous asteroid radar observations. |