2839 Annette

2839 Annette (prov. designation: ) is a bright Flora asteroid from the inner regions of the asteroid belt. It was discovered on 5 October 1929, by American astronomer Clyde Tombaugh at Lowell Observatory during his search for Pluto. The presumed S-type asteroid has a rotation period of 10.5 hours and measures approximately 5 km in diameter. It was named after the discoverer's daughter.

Orbit and classification
Annette is a S-type asteroid and member of the Flora family, one of the largest families of stony asteroids. It orbits the Sun in the inner main-belt at a distance of 1.9–2.5 AU once every 3 years and 4 months (1,205 days). Its orbit has an eccentricity of 0.15 and an inclination of 5° with respect to the ecliptic. Due to a precovery taken at Lowell Observatory, the body's observation arc was extended by 4 days prior to its official discovery observation.

Naming
This minor planet was named after Clyde Tombaugh's daughter, Annette. The approved naming citation was published by the Minor Planet Center on 22 June 1986 (M.P.C. 10845).

Rotation period


The first rotational lightcurve of Annette was obtained by American astronomer Brian Warner at his Palmer Divide Observatory, Colorado, in December 2005. It gave a rotation period of 10.457 hours with a brightness variation of 0.92 magnitude (U=3-). In November 2006, a second lightcurve by astronomer Robert Buchheim at Altimira Observatory in southern California gave a concurring period of 10.4595 hours and an amplitude of 0.64 magnitude (U=3). He also noted a significantly fainter absolute magnitude of 14.35 than previously reported.

Diameter and albedo
According to the survey carried out by NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Annette measures between 5.41 and 7.562 kilometers in diameter and its surface has an albedo between 0.056 and 0.47, while the Collaborative Asteroid Lightcurve Link assumes an albedo of 0.24 – derived from 8 Flora, the largest member and namesake of its family – and calculates a diameter of 3.66 kilometers using Robert Buchheim's fainter absolute magnitude of 14.35.