2114 Wallenquist

2114 Wallenquist, provisional designation, is a Themistian asteroid from the outer region of the asteroid belt, approximately 28 kilometers in diameter. It was discovered by Swedish astronomer Claes-Ingvar Lagerkvist at the Australian Mount Stromlo Observatory near Canberra, on 19 April 1976.

Orbit and classification
Wallenquist is a member of the Themis family, a dynamical family of outer-belt asteroids with nearly coplanar ecliptical orbits. It orbits the Sun in the outer main-belt at a distance of 2.7–3.7 AU once every 5 years and 9 months (2,090 days). Its orbit has an eccentricity of 0.14 and an inclination of 1° with respect to the ecliptic. The first used observation was made at the U.S. Goethe Link Observatory in 1953, extending the asteroid's observation arc by 23 years prior to its discovery.

Rotation period
In April 2010, a rotational lightcurve of Wallenquist obtained by American astronomer Robert Stephens at the Goat Mountain Astronomical Research Station (GMARS, G79), California, gave a well-defined rotation period of $21.12$ hours with a brightness amplitude of 0.22 magnitude (U=3).

Two other observations, by French astronomer René Roy at Blauvac Observatory (627), France, and by astronomers at the U.S. Palomar Transient Factory, gave a period of $22.558$ and $23.008$, with an amplitude of 0.30 and 0.23, respectively (U=2/2).

Diameter and albedo
According to the surveys carried out by the Infrared Astronomical Satellite, IRAS, the Japanese Akari satellite, and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Wallenquist measures between 21.1 and 27.6 kilometers in diameter while its surface has an albedo in the range of 0.08 and 0.15.

The Collaborative Asteroid Lightcurve Link (CALL) derives an even lower albedo of 0.04 and calculates a diameter of 27.5 kilometer. Despite its low albedo, CALL characterizes the body as a S-type rather than a darker C-type asteroid.

Naming
This minor planet was named in honor of Swedish astronomer Åke Wallenquist (1904–1994), former director of the Kvistaberg Station, after which the minor planet 3331 Kvistaberg is named.

After his retirement Wallenquist continued to research dark matter in open clusters at the Uppsala Astronomical Observatory. He co-discovered the near-Earth Amor asteroid 1980 Tezcatlipoca during his stay at the Palomar Observatory in California in 1950. The official was published by the Minor Planet Center on 1 February 1979 (M.P.C. 4645).