Discovered by J. A. Bruwer Observation arc 76.60 yr (27,978 days) Inclination 9.0943° Discoverer Jacobus A. Bruwer Discovery site Union Observatory | Discovery date 13 July 1953 Minor planet category main-belt · (middle) Discovered 13 July 1953 Orbits Sun Asteroid group Asteroid belt | |
Alternative names 1953 NA · 1940 GB1948 EM · 1949 QA1953 OF · 1953 PN1957 OE | ||
1658 Innes, provisional designation 1953 NA, is a rare-type asteroid from the middle region of the asteroid belt, approximately 15 kilometers in diameter. It was discovered on 13 July 1953, by South African astronomer Jacobus Bruwer at Johannesburg Observatory in South Africa.
In the Tholen taxonomy, Innes has an AS-spectral type, an intermediate form of the rare A-types to the common stony asteroids (also see category listing). It orbits the Sun at a distance of 2.1–3.0 AU once every 4 years and 1 month (1,495 days). Its orbit has an eccentricity of 0.18 and an inclination of 9° with respect to the ecliptic. Innes was first identified as 1940 GB at Turku Observatory in 1940, extending the body's observation arc by 13 years prior to its official discovery observation.
In May 2005, astronomers Robert D. Stephens at the Center for Solar System Studies, California, and Lorenzo Franco at Balzaretto Observatory, near Rome, each obtained a rotational light-curve of Innes. The photometric observations gave an identical rotation period of 7000319100000000000♠3.191±0.001 hours with a brightness variation of 0.22 and 0.25 magnitude, respectively (U=3/3).
According to the 2014-revised survey result of NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Innes measures 13.35 kilometers in diameter and its surface has an albedo of 0.248, while the Collaborative Asteroid Lightcurve Link assumes a standard albedo for stony asteroids of 0.20 and calculates a diameter of 14.76 kilometers using an absolute magnitude of 11.52.
This minor planet was named for Scottish–South African astronomer Robert T. A. Innes (1861–1933), first director of the discovering Union Observatory from 1903 to 1927 (originally named Transvaal Observatory). He was a skilled observational astronomer, famous for his deliberate search and discovery of the nearest star, Proxima Centauri, in 1915. He also made important theoretical and computational contributions to celestial mechanics and to the irregular rotation of the Earth. The astronomer is also honored by the lunar crater Innes. Naming citation was published before November 1977 (M.P.C. 3297).
Innes was the first numbered discovery of astronomer Jacobus Bruwer. In addition, he also discovered the minor planets 1660 Wood, 1794 Finsen, and 3284 Niebuhr. The asteroid 1811 Bruwer was named in his honour by the Dutch, Dutch-American astronomer trio of the Palomar–Leiden survey.