_Sein%25C3%25A4joki.png) Shape model of Seinäjoki from itslightcurve | |
| Discovery[1] | |
|---|---|
| Discovered by | Y. Väisälä |
| Discovery site | Turku Obs. |
| Discovery date | 22 October 1938 |
| Designations | |
| (1521) Seinäjoki | |
Named after | Seinäjoki(Finnish city)[2] |
| 1938 UB1 · 1933 UR1 1967 UW | |
| main-belt · (outer)[3] Brasilia[4] | |
| Orbital characteristics[1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 78.62 yr (28,716 days) |
| Aphelion | 3.2435AU |
| Perihelion | 2.4633 AU |
| 2.8534 AU | |
| Eccentricity | 0.1367 |
| 4.82yr (1,760 days) | |
| 123.44° | |
| 0° 12m 16.2s / day | |
| Inclination | 15.059° |
| 12.593° | |
| 48.805° | |
| Physical characteristics | |
| 13.66±3.61 km[5] 14.813±0.070 km[6] 16.095±0.070 km[7] 16.29±0.20 km[8] 24.30 km(calculated)[3] | |
| 4.32±0.01 h[9] 4.328159±0.000001 h[10] | |
| 0.057(assumed)[3] 0.116±0.018[8] 0.1733±0.0300[7] 0.205±0.015[6] 0.22±0.12[5] | |
| C[3] | |
| 11.5[7] · 11.8[1][3] · 11.90[8] · 11.92[5] · 12.17±0.45[11] | |
1521 Seinäjoki (provisional designation1938 UB1) is a Brasiliaasteroid from the outer region of theasteroid belt, approximately 14 kilometers in diameter. It was discovered on 22 October 1938, by Finnish astronomerYrjö Väisälä at the southwesternTurku Observatory, Finland.[12] The asteroid was later named after the Finnish city ofSeinäjoki.[2]
Seinäjoki is a member of theBrasilia family, a smallerasteroid family ofX-type asteroids in theouter main-belt. Since the family's namesake,293 Brasilia, is a suspectedinterloper in its own family, it has also been namedSeinäjoki family after Seinäjoki.[4][13]: 37
It orbits the Sun in theouter main-belt at a distance of 2.5–3.2 AU once every 4 years and 10 months (1,760 days). Its orbit has aneccentricity of 0.14 and aninclination of 15° with respect to theecliptic.[1] In 1933, Seinäjoki was first identified as1933 UR1 atSimeiz Observatory. The body'sobservation arc, however, begins with its official discovery observation at Turku.[12]
In October 2010, a rotationallightcurve of Seinäjoki was obtained by Russell Durkee at the U.S. Shed of Science Observatory (H39) in Minneapolis. It gave it a well-definedrotation period of 4.32 hours with a brightness variation of 0.15magnitude (U=3).[9] A modeled lightcurve form Lowell photometric database gave a concurring period of 4.328 hours and a spin axis of (-18.0°, 230.0°) inecliptic coordinates.[10]
According to the survey carried out by NASA'sWide-field Infrared Survey Explorer (WISE) with its subsequentNEOWISE mission, Seinäjoki measures between 13.66 and 14.81 kilometers in diameter, and its surface has analbedo between 0.205 and 0.22 (more recent results only).[5][6][7][8]
TheCollaborative Asteroid Lightcurve Link assumes a standard albedo for carbonaceousC-type asteroids of 0.057 and calculates a much larger diameter of 24.30 kilometers as a body's and diameter and reflectivity (albeo) correlate indirectly.[3] However, based on the much higher albedo given by WISE/NEOWISE, the body is rather of astony composition, which is untypical for asteroids in the outer main-belt.
Thisminor planet was named for the city ofSeinäjoki, located inSouthern Ostrobothnia, western Finland.[2] The officialnaming citation was published by theMinor Planet Center on 20 February 1976 (M.P.C. 3929).[14]
