980 Anacostia

980 Anacostia is a minor planet orbiting the Sun that was discovered by American astronomer George Henry Peters on 21 November 1921. The name recognizes the Anacostia River and an historic neighborhood of the same name in the city of Washington, D.C.^{[citation needed]}

980 Anacostia

Orbit diagram of 980 Anacostia
Discovery
Discovered by	George Henry Peters
Discovery site	Washington, D.C.
Discovery date	21 November 1921
Designations
MPC designation	(980) Anacostia
Pronunciation	/ænəˈkɒstiə/[1]
Alternative designations	1921 W19
Orbital characteristics[2]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc	87.01 yr (31782 days)
Aphelion	3.2953 AU (492.97 Gm)
Perihelion	2.1842 AU (326.75 Gm)
Semi-major axis	2.7397 AU (409.85 Gm)
Eccentricity	0.20278
Orbital period (sidereal)	4.53 yr (1656.4 d)
Mean anomaly	317.515°
Mean motion	0° 13m 2.424s / day
Inclination	15.905°
Longitude of ascending node	285.817°
Argument of perihelion	70.143°
Physical characteristics
Mean radius	43.095±0.8 km
Synodic rotation period	20.117 h (0.8382 d)
Geometric albedo	0.1723±0.006
Absolute magnitude (H)	7.85

Measurements using the adaptive optics system at the W. M. Keck Observatory give a diameter of 70 ± 6 km. This is 23% smaller than the diameter estimated from the IRAS observatory data. The size ratio between the major and minor axes is 1.09.^[3]

Polarimetric study of this asteroid reveals anomalous properties that suggests the regolith consists of a mixture of low and high albedo material. This may have been caused by fragmentation of an asteroid substrate with the spectral properties of CO3/CV3 carbonaceous chondrites.^[4]