16765 Agnesi

16765 Agnesi (provisional designation 1996 UA) is a stony Eunomia asteroid from the middle region of the asteroid belt, approximately 4 kilometers in diameter. It was discovered on 16 October 1996, by Italian-American amateur astronomer Paul Comba at his private Prescott Observatory in Arizona, United States.^[8] The asteroid was named after Italian mathematician Maria Gaetana Agnesi.^[2]

16765 Agnesi

Discovery[1]
Discovered by	P. G. Comba
Discovery site	Prescott Obs.
Discovery date	16 October 1996
Designations
MPC designation	(16765) Agnesi
Named after	Maria Agnesi (Italian mathematician)[2]
Alternative designations	1996 UA
Minor planet category	main-belt · Eunomia[3]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc	19.88 yr (7,261 days)
Aphelion	2.9139 AU
Perihelion	2.3361 AU
Semi-major axis	2.6250 AU
Eccentricity	0.1101
Orbital period (sidereal)	4.25 yr (1,553 days)
Mean anomaly	4.2373°
Mean motion	0° 13m 54.12s / day
Inclination	12.266°
Longitude of ascending node	17.764°
Argument of perihelion	314.93°
Physical characteristics
Dimensions	3.84 km (calculated)[3] 4.132±0.247 km[4][5]
Synodic rotation period	7.5458±0.0034 h[6]
Geometric albedo	0.21 (assumed)[3] 0.2849±0.0250[4] 0.285±0.025[5]
Spectral type	S[3]
Absolute magnitude (H)	13.9[1][4] · 13.30±0.00[7] · 13.943±0.004 (R)[6] · 14.39[3]

Orbit and classification

Agnesi is a member of the Eunomia family, a large group of S-type asteroids and the most prominent family in the central main-belt. It orbits the Sun at a distance of 2.3–2.9 AU once every 4 years and 3 months (1,553 days). Its orbit has an eccentricity of 0.11 and an inclination of 12° with respect to the ecliptic.^[1] It was first observed by Haleakala–NEAT/GEODSS (566), extending the asteroid's observation arc by 32 days prior to its official discovery observation.^[8]

Physical characteristics

Diameter and albedo

According to the NEOWISE mission of NASA's space-based Wide-field Infrared Survey Explorer, Agnesi measures 4.1 kilometers in diameter and its surface has an albedo of 0.28,^[4] while the Collaborative Asteroid Lightcurve Link assumes an albedo of 0.21 – derived from 15 Eunomia, the family's largest member and namesake – and calculates a diameter of 3.8 kilometers.^[3]

Lightcurves

A rotational lightcurve of Agnesi was obtained from photometric observations taken by astronomers at the Palomar Transient Factory in September 2013. Lightcurve analysis gave a rotation period of 7.5458 hours with a brightness variation of 0.31 magnitude (U=2).^[6]

Naming

This minor planet was named in honor of Italian Maria Gaetana Agnesi (1718–1799), who was the first Western woman to write a widely translated mathematics handbook and the first woman appointed to a professorship at a university in 1750.^[2] The official naming citation was published by the Minor Planet Center on 9 January 2001 (M.P.C. 41941).^[9]