Discovered by Y. Väisälä MPC designation 1473 Ounas Discovered 22 October 1938 Orbits Sun Discovery site Iso-Heikkilä Observatory | Discovery date 22 October 1938 Minor planet category main-belt · (middle) Absolute magnitude 11.8 Discoverer Yrjö Väisälä Asteroid group Asteroid belt | |
Named after Ounas river (in Finland) Alternative names 1938 UT · 1950 NZ
1950 PB1 People also search for 1478 Vihuri, 1479 Inkeri, 1471 Tornio | ||
1473 Ounas, provisional designation 1938 UT, is a stony asteroid and slow rotator from the middle region of the asteroid belt, approximately 18 kilometers in diameter. It was discovered on 22 October 1938, by Finnish astronomer Yrjö Väisälä at Turku Observatory in Southwest Finland.
Ounas is a S-type asteroid orbiting the Sun at a distance of 2.0–3.2 AU once every 4 years and 2 months (1,509 days). Its orbit has an eccentricity of 0.24 and an inclination of 14° with respect to the ecliptic. As no precoveries were taken, and no previous identifications were made, the body's observation arc begins with its official discovery observation in 1938.
In October 2012/13, a rotational light-curve of Ounas was obtained from photometric observations by astronomers René Roy, Vladimir Benishek, Andrea Ferrero, Daniel Klinglesmith, Frederick Pilcher, Raoul Behrend and Petr Pravec. It gave a well-defined rotation period of 139.1 hours with a brightness variation of 0.6 magnitude (U=3/3). Ounas is a suspected "tumbler", which have a non-principal axis rotation (NPAR).
According to the survey carried out by NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, the asteroid measures 18.16 kilometers in diameter and its surface has an albedo of 0.11. The Collaborative Asteroid Lightcurve Link derives an albedo of 0.1189 and a diameter of 17.62 kilometers, using an absolute magnitude of 11.7.
The minor planet was named after the Ounas river, one of the principal rivers in Finland. Naming citation was published before November 1977 (M.P.C. 3928).