9000 Hal
9000 Hal, provisional designation, is a stony background asteroid and slow rotator from the inner regions of the asteroid belt, approximately in diameter. It was discovered on 3 May 1981, by American astronomer Edward Bowell at Lowell's Anderson Mesa Station near Flagstaff, Arizona, in the United States. The likely elongated S-type asteroid has an exceptionally long rotation period of 908 hours. It was named after the fictional supercomputer HAL 9000, featured in the 1968 film 2001: A Space Odyssey.
Orbit and classification
Hal is a non-family asteroid of the main belt's background population when applying the hierarchical clustering method to its proper orbital elements. Based on osculating Keplerian orbital elements, the asteroid has also been classified as a member of the Flora family, a giant asteroid family and the largest family of stony asteroids in the main-belt.Hal orbits the Sun in the inner asteroid belt at a distance of 1.8–2.7 AU once every 3 years and 4 months. Its orbit has an eccentricity of 0.21 and an inclination of 6° with respect to the ecliptic. The asteroid was first observed as at Crimea–Nauchnij in November 1975. The body's observation arc begins with its official discovery observation at Anderson Mesa in May 1981.
Physical characteristics
Hal is an assumed stony S-type asteroid, based on the Collaborative Asteroid Lightcurve Link classification into the Flora family.Rotation period
In August 2008, a rotational lightcurve of Hal was obtained from photometric observations by Slovak astronomers Adrián Galád, Jozef Világi, Leonard Kornoš and Štefan Gajdoš at Modra Observatory. Lightcurve analysis gave an exceptionally long rotation period of 908 hours with a high brightness variation of 0.9 magnitude. This makes Hal one of the slowest rotators known to exist. In addition, the body's high brightness amplitude is indicative of a non-spherical shape.An alternative measurement by French amateur astronomers Pierre Antonini and René Roy gave a much shorter period of 22.68 hours. The result, however, is considered of poor quality by CALL.