2741 Valdivia

2741 Valdivia (prov. designation: ) is a background asteroid from the central regions of the asteroid belt, approximately 11 km in diameter. It was discovered on 1 December 1975, by Chilean astronomers Carlos Torres and Sergio Barros at the Cerro El Roble Station northwest of Santiago de Chile. The asteroid was named after Spanish conquistador Pedro de Valdivia.

Orbit and classification
Valdivia is a non-family asteroid from the main belt's background population. It orbits the Sun in the central main-belt at a distance of 2.1–3.1 AU once every 4 years and 3 months (1,540 days). Its orbit has an eccentricity of 0.18 and an inclination of 10° with respect to the ecliptic. The asteroid was first observed as at Uccle Observatory in February 1935, where the body's observation arc begins just a two weeks later, or more than 40 years before its official discovery observation at Cerro El Roble.

Naming
This minor planet was named after Spanish conquistador Pedro de Valdivia (1502–1553), who conquered Chile with a small expedition corps after he served under Francisco Pizarro in Peru. Valdivia founded the cities Santiago (1541) and Concepción (1550) and became Chile's first royal governor. The city of Valdivia in southern Chile is also named after him. The official naming citation was published by the Minor Planet Center on 26 March 1986 (M.P.C. 10546).

Rotation period
In August 2016, the so-far best-rated rotational lightcurve of Valdivia was obtained by the Spanish amateur astronomer group OBAS. Lightcurve analysis gave a rotation period of 4.098 hours with a brightness variation of 0.25 magnitude (U=3). Previously, in May 2003, photometric observations made by Donald P. Pray at the Carbuncle Hill Observatory near Providence, Rhode Island, gave a synodic period of 4.096 hours and an amplitude of 0.40 in magnitude (U=2+). In addition astronomers at the Palomar Transient Factory found a period of 4.096 hours with an amplitude of 0.28 om May 2011 (U=2), and French amateur astronomer René Roy obtained a period of 8.1922 hours (twice the period solution) with an amplitude of 0.36 (U=2).

Poles
In 2016, an international study modeled a lightcurve with a concurring period of $9.13$ hours and found two spin axes of (269.0°, −31.0°) and (103.0°, −59.0°) in ecliptic coordinates (λ,&thinsp;β) (U=n.a.).

Diameter and albedo
According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Valdivia measures between 9.13 and 11.679 kilometers in diameter and its surface has an albedo between 0.205 and 0.404, while the Japanese Akari satellite found an albedo of 0.244 and a diameter of 10.73 kilometers. The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.10 – a compromise value between the carbonaceous (0.057) and stony (0.20) asteroids – and calculates a diameter of 17.52 kilometers based on an absolute magnitude of 11.9.