Minor planet category
main-belt · Eunomia
14 March 1999
Brač (Croatian island)
14 March 1999
1999 ES4 · 1962 TN 1968 BF · 1975 TJ1 1980 YK · 1986 EH5 1988 SX4
Sun, 390 Alma, 85 Io
Valentino boskovic feat nemanja pridjevi 10645 bra
10645 Brač, provisional designation 1999 ES4, is a stony Eunomia asteroid from the middle region of the asteroid belt, approximately 10 kilometers in diameter. It was discovered by Croatian astronomer Korado Korlević at Višnjan Observatory, Croatia, on 14 March 1999.
The asteroid is a member of the Eunomia family, a large group of S-type asteroids and the most prominent family in the intermediate main-belt. It orbits the Sun at a distance of 2.2–3.1 AU once every 4 years and 4 months (1,584 days). Its orbit has an eccentricity of 0.18 and an inclination of 13° with respect to the ecliptic. The first precovery was taken at the U.S. Goethe Link Observatory in 1962, extending the asteroid's observation arc by 37 years prior to discovery.
In October 2014, photometric observations by Italian astronomer Silvano Casulli gave a rotational light-curve with a period of 7000278592000000000♠2.78592±0.00003 hours and a brightness amplitude of 0.31 in magnitude (U=3-). Three weeks later, a second light-curve was obtained at the U.S. Etscorn Campus Observatory in New Mexico, rendering a concurring period of 7000278500000000000♠2.785±0.005 with an identical variation in brightness (U=3-).
According to the survey carried out by NASA's space-based Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, the asteroid measures 10.3 kilometers in diameter and its surface has an albedo of 6999202000000000000♠0.202±0.038, while the Collaborative Asteroid Lightcurve Link assumes an albedo of 0.21 and calculates a diameter of 9.6 kilometers. A large-scale survey by Pan-STARRS (PS1) assigns an LS-type, presumably an intermediary spectral type between common stony S-types and the rather rare and reddish L-type asteroids.
The minor planet was named after the Croatian island of Brač, the largest Dalmatian island in the Adriatic sea, and the place where the Blaca hermitage Observatory is located. Naming citation was published on 15 December 2005 (M.P.C. 55720).