2008 HJ is a sub-kilometer asteroid, classified as near-Earth object of the Apollo group.
Observers M. Bezpalko, D. Torres, R. Kracke, G. Spitz, J. Kistler.
Richard Miles using the Faulkes Telescope South at Siding Spring Observatory, Australia determined that the asteroid rotates rapidly.
At the time of discovery, 2008 HJ had the smallest known rotation period in the Solar System, completing one revolution every 42.7 seconds.
[1][2] It is listed on the Sentry Risk Table with a 1 in 17,000 chance of impacting Earth on May 2, 2081.