1523 Pieksämäki
Florian asteroid
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1523 Pieksämäki (provisional designation 1939 BC) is a stony Florian asteroid from the inner regions of the asteroid belt, approximately 9 kilometers in diameter. It was discovered on 18 January 1939, by Finnish astronomer Yrjö Väisälä at the Turku Observatory in Southwest Finland, and named for the town of Pieksämäki.[2][12]
| Discovery[1] | |
|---|---|
| Discovered by | Y. Väisälä |
| Discovery site | Turku Obs. |
| Discovery date | 18 January 1939 |
| Designations | |
| (1523) Pieksamaki | |
Named after | Pieksämäki (Finnish town)[2] |
| 1939 BC · 1936 FO1 1936 HC · 1946 GB 1949 AC | |
| main-belt · Flora[3] | |
| Orbital characteristics[1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 80.20 yr (29,294 days) |
| Aphelion | 2.4509 AU |
| Perihelion | 2.0327 AU |
| 2.2418 AU | |
| Eccentricity | 0.0933 |
| 3.36 yr (1,226 days) | |
| 131.04° | |
| Inclination | 5.1411° |
| 327.79° | |
| 187.58° | |
| Physical characteristics | |
| Dimensions | 8.98 km (calculated)[3] 9.111±0.313 km[4] 10.008±0.057 km[5] |
| 5.3202±0.0005 h[6][7] 5.3210±0.0001 h[8] 5.33 h[9] | |
| 0.2135±0.0277[5] 0.24 (assumed)[3] 0.281±0.041[10] 0.505±0.294[4] | |
| S[3] | |
| 11.56[4] · 12.3[5] · 12.4[1][3] · 12.58±0.53[11] | |
Orbit and classification
This S-type asteroid is a member of the Flora family, one of the largest groups of stony asteroids in the main-belt. It orbits the Sun at a distance of 2.0â2.5 AU once every 3 years and 4 months (1,226 days). Its orbit has an eccentricity of 0.09 and an inclination of 5° with respect to the ecliptic.[1] In 1936, it was first identified as 1936 FO1 at Nice Observatory, extending Pieksämäki's observation arc by 3 years prior to its official discovery observation at Turku.[12]
Physical characteristics
Lightcurves
In December 2005, American amateur astronomer Donald P. Pray obtained a rotational lightcurve at Carbuncle Hill Observatory in collaboration with other astronomers. Light-curve analysis gave a well-defined rotation period of 5.3202 hours with a brightness variation of 0.47 magnitude (U=3).[6]
Previous photometric observations were made by KryszczyÅska et al. in July 2004, that gave an identical period with an amplitude of 0.40 magnitude (U=2+),[7] and by Claes-Ingvar Lagerkvist, who derived a period of 5.33 hours (Î0.5 mag) already in the 1970s (U=2).[9] In March 2013, another well-defined period of 5.3210 hours (Î0.42 mag) was obtained by French amateur astronomer René Roy.[8]
Diameter and albedo
According to the surveys carried out by NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Pieksämäki measures 9.111 and 10.008 kilometers in diameter, and its surface has an albedo between 0.213 and 0.505.[4][5][10] The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.24 â derived from 8 Flora, the family's principal body and namesake â and calculates a diameter of 8.98 kilometers based on an absolute magnitude of 12.4.[3]
Naming
This minor planet was named for Pieksämäki, an eastern Finnish town in Southern Savonia.[2] The official naming citation was published by the Minor Planet Center on 20 February 1976 (M.P.C. 3929).[13]