| Discovery[1] | |
|---|---|
| Discovered by | Y. Väisälä |
| Discovery site | Turku Obs. |
| Discovery date | 22 October 1938 |
| Designations | |
| (1473) Ounas | |
Named after | Ounasjoki River (in Finland)[2] |
| 1938 UT · 1950 NZ 1950 PB1 | |
| main-belt · (middle)[3] | |
| Orbital characteristics[1] | |
| Epoch 16 February 2017 (JD 2457800.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 77.90 yr (28,452 days) |
| Aphelion | 3.1862AU |
| Perihelion | 1.9623 AU |
| 2.5743 AU | |
| Eccentricity | 0.2377 |
| 4.13yr (1,509 days) | |
| 19.843° | |
| 0° 14m 18.96s / day | |
| Inclination | 13.651° |
| 216.52° | |
| 129.42° | |
| Physical characteristics | |
| Dimensions | 17.62 km(derived)[3] 18.164±0.109[4] 20.032 km(dated)[5] |
| 16h(dated)[3] 139.1±0.1 h[6] 139.1±0.5 h[7] | |
| 0.0841(dated)[5] 0.110±0.018[4] 0.1189(derived)[3] | |
| S[3] | |
| 11.67±0.32[8] · 11.7[1][3] · 11.8[5] | |
1473 Ounas, provisional designation1938 UT, is a stonyasteroid, suspected tumbler and aslow rotator from the middle region of theasteroid belt, approximately 18 kilometers in diameter. It was discovered on 22 October 1938, by Finnish astronomerYrjö Väisälä atTurku Observatory in Southwest Finland.[9] The asteroid was named after the FinnishOunas river.[2]
Ounas is aS-type asteroid that orbits the Sun in thecentral main-belt at a distance of 2.0–3.2 AU once every 4 years and 2 months (1,509 days). Its orbit has aneccentricity of 0.24 and aninclination of 14° with respect to theecliptic.[1] As noprecoveries were taken, and no previous identifications were made, the body'sobservation arc begins with its official discovery observation at Turku in 1938.[9]
In October 2012/13, a rotationallightcurve ofOunas was obtained from photometric observations by astronomersRené Roy, Vladimir Benishek, Andrea Ferrero, Daniel Klinglesmith,Frederick Pilcher,Raoul Behrend andPetr Pravec. It gave a well-definedrotation period of 139.1 hours with a brightness variation of 0.6magnitude (U=3/3).[6][7]Ounas is a suspected "tumbler", which have a non-principal axis rotation (NPAR).[6]
According to the survey carried out by NASA'sWide-field Infrared Survey Explorer with its subsequentNEOWISE mission, the asteroid measures 18.16 kilometers in diameter and its surface has analbedo of 0.11.[4][5] TheCollaborative Asteroid Lightcurve Link derives an albedo of 0.1189 and a diameter of 17.62 kilometers with anabsolute magnitude of 11.7.[3]
Thisminor planet was named after theOunas river, one of the principal rivers in Finland.[2] The officialnaming citation was published by theMinor Planet Center on 20 February 1976 (M.P.C. 3928).[10]
