16765 Agnesi (provisional designation ) 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. The asteroid was named after Italian mathematician Maria Gaetana Agnesi.
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 2.3âÂÂ2.9 AU once every 4 years and 3 months (1,553 days). Its orbit has an eccentricity of 0.11 and an inclination of 12ð with respect to the ecliptic. It was first observed by HaleakalaâÂÂNEAT/GEODSS (), extending the asteroid's observation arc by 32 days prior to its official discovery observation.
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, while the Collaborative Asteroid Lightcurve Link assumes an albedo of 0.21 â derived from 15 Eunomia, the family's largest member and namesake â and calculates a diameter of 3.8 kilometers.
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 hours with a brightness variation of magnitude ().
This minor planet was named in honor of Italian Maria Gaetana Agnesi (1718âÂÂ1799), 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. The official naming citation was published by the Minor Planet Center on 9 January 2001 ().