Discovered by E. F. Helin MPC designation 6522 Aci Absolute magnitude 12.8 Discoverer Eleanor F. Helin Asteroid group Asteroid belt | Discovery date 9 July 1991 Alternative names 1991 NQ · 1990 BH4 Discovered 9 July 1991 Orbits Sun | |
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6522 Aci, provisional designation 1991 NQ, is a stony Phocaea asteroid from the inner regions of the asteroid belt, about 6 kilometers in diameter. It was discovered by American astronomer Eleanor Helin at the U.S. Palomar Observatory in California, on 9 July 1991.
The S-type asteroid is a member of the Phocaea family, a relatively small group of asteroids with similar orbital characteristics. It orbits the Sun at a distance of 1.9–2.9 AU once every 3 years and 8 months (1,345 days). Its orbit has an eccentricity of 0.20 and an inclination of 22° with respect to the ecliptic. The first precovery was taken at the German Karl Schwarzschild Observatory in 1990, one year prior to its discovery.
A photometric light-curve analysis performed at the U.S. Palomar Transient Factory in 2010, rendered a rotation period of 7000769210000000000♠7.6921±0.0017 hours with a brightness amplitude of 0.68 in magnitude (U=2). According to the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, the asteroid measures 6.1 kilometers in diameter and its surface has a high albedo of 0.39, while the Collaborative Asteroid Lightcurve Link assumes an albedo of 0.23 – which derives from 25 Phocaea, namesake and largest member of this orbital family – and calculates a diameter of 5.7 kilometers.
The minor planet was named for the river southeast of Mount Etna in Sicily, Italy. The towns and villages along the river, such as Aci Castello, Aci Trezza, Aci-Reale, and Aci Sant'Antonio, were also honored. The river also brings to mind the myth of Aci from Greek mythology, which is about a young Sicilian shepherd, who was killed by the jealous cyclops Polyphemus, because of his love for the sea nymph Galatea. The minor planet 74 Galatea is named after this Nereid. Naming citation was published on 26 October 1996 (M.P.C. 28090).