2839 Annette

2839 Annette (prov. designation: 1929 TP) 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.^[9] The presumed S-type asteroid has a rotation period of 10.5 hours and measures approximately 5 kilometers (3.1 miles) in diameter. It was named after the discoverer's daughter.^[2]

2839 Annette

Shape model of Annette from its lightcurve
Discovery [1]
Discovered by	C. W. Tombaugh
Discovery site	Lowell Obs.
Discovery date	5 October 1929
Designations
MPC designation	(2839) Annette
Named after	Annette Tombaugh (discoverer's daughter)[2]
Alternative designations	1929 TP · 1937 AB1 1939 UL · 1962 TE 1970 BB · 1972 XF1 1982 VP
Minor planet category	main-belt · Flora [3]
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc	87.67 yr (32,023 days)
Aphelion	2.5493 AU
Perihelion	1.8838 AU
Semi-major axis	2.2166 AU
Eccentricity	0.1501
Orbital period (sidereal)	3.30 yr (1,205 days)
Mean anomaly	200.55°
Mean motion	0° 17m 55.32s / day
Inclination	4.8085°
Longitude of ascending node	44.569°
Argument of perihelion	6.8264°
Physical characteristics
Mean diameter	5.41±0.86 km[4] 7.313±0.150 km[5] 7.562±0.122 km[6]
Synodic rotation period	10.457±0.003 h[7] 10.4595±0.0001 h[8]
Geometric albedo	0.0563±0.0118[6] 0.060±0.005[5] 0.24 (assumed)[3] 0.47±0.22[4]
Spectral type	S [3]
Absolute magnitude (H)	12.9[1] · 12.92[4] · 14.35[3][6][8]

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.^[1] Due to a precovery taken at Lowell Observatory, the body's observation arc was extended by 4 days prior to its official discovery observation.^[9]

Naming

This minor planet was named after Clyde Tombaugh's daughter, Annette.^[2] The approved naming citation was published by the Minor Planet Center on 22 June 1986 (M.P.C. 10845).^[10]

Physical characteristics

Rotation period

Lightcurve-based 3D-model of Annette

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-).^[7] 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.^[8]

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,^[4][5][6] 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.^[3]