4606 Saheki

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4606 Saheki
4606Saheki (Lightcurve Inversion).png
Light-curve based 3D-model of 4606 Saheki
Discovery [1]
Discovered by T. Seki
Discovery site Geisei Obs.
Discovery date 27 October 1987
MPC designation 4606 Saheki
Named after
Tsuneo Saheki
1987 UM1 · 1972 GA1
1977 TJ7 · 1977 VF2
1982 FH4
main-belt · Flora[3]
Orbital characteristics[1]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc 62.67 yr (22,889 days)    
Aphelion 2.4807 AU
Perihelion 2.0226 AU
2.2517 AU
Eccentricity 0.1017
3.38 yr (1,234 days)
0° 17m 29.76s / day
Inclination 2.6336°
Physical characteristics
Dimensions 6.712±0.041 km[4]
7.14 km (calculated)[3]
4.969±0.003 h[a]
5.032±0.001 h[5]
4.97347±0.00005 h[6]
0.24 (assumed)[3]

4606 Saheki, provisional designation 1987 UM1, is a stony Flora asteroid from the inner regions of the asteroid belt, about 7 kilometers in diameter. It was discovered by Japanese astronomer Tsutomu Seki at Geisei Observatory, Japan, on 27 October 1987.[8]

The 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 2.0–2.5 AU once every 3 years and 5 months (1,234 days). Its orbit hs an eccentricity of 0.10 and an inclination of 3° with respect to the ecliptic.[1] The first precovery was taken at Palomar Observatory in 1953, extending the asteroid's observation arc by 34 years prior to its discovery.[8]

In January 2009, a photometric light-curve analysis by David Higgins at Hunters Hill Observatory, Australia, rendered a well-defined rotation period of 4.969±0.003 hours with a brightness variation of 0.56 in magnitude (U=3).[a] Two months later, in March 2009, a second light-curve was obtained at the Via Capote Observatory, California, gave a period of 5.032±0.001 and an amplitude of 0.68 in magnitude (U=3-).[5] According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, the asteroid has a high albedo of 0.33 and a diameter of 6.7 kilometers, while the Collaborative Asteroid Lightcurve Link (CALL) calculates a diameter of 7.1 kilometers, based on an assumed albedo of 0.24, which is identical to the albedo of the Flora family's namesake, the asteroid 8 Flora.[3][4]

The minor planet was named after Japanese astronomer and president of the Toa Astronomical Society, Tsuneo Saheki (1916–1996). Over half a century, he as gathered large inventory of observational data of the planet Mars.[2] The Martian crater Saheki is also named in his honour. Naming citation was published on 28 May 1991 (M.P.C. 18308).[9]


  1. ^ a b Higgins (2011) web: rotation period 4.969±0.003 hours with a brightness amplitude of 0.56 mag. The Collaborative Asteroid Lightcurve Link assigns a quality code of U=3 to the period solution, which denotes a secure result within the precision given and no ambiguity. Summary figures at Collaborative Asteroid Lightcurve Link (CALL) for (4606) Saheki
  1. ^ a b c d "JPL Small-Body Database Browser: 4606 Saheki (1987 UM1)" (2016-04-16 last obs.). Jet Propulsion Laboratory. Retrieved 26 April 2016. 
  2. ^ a b Schmadel, Lutz D. (2007). Dictionary of Minor Planet Names – (4606) Saheki. Springer Berlin Heidelberg. p. 396. ISBN 978-3-540-00238-3. Retrieved 23 January 2016. 
  3. ^ a b c d e f "LCDB Data for (4606) Saheki". Asteroid Lightcurve Database (LCDB). Retrieved 23 January 2016. 
  4. ^ a b c d Mainzer, A.; Grav, T.; Masiero, J.; Hand, E.; Bauer, J.; Tholen, D.; et al. (November 2011). "NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results". The Astrophysical Journal. 741 (2): 25. arXiv:1109.6407free to read. Bibcode:2011ApJ...741...90M. doi:10.1088/0004-637X/741/2/90. Retrieved 23 January 2016. 
  5. ^ a b Brinsfield, James W. (July 2009). "Asteroid Lightcurve Analysis at the Via Capote Observatory: 2009 1st Quarter". The Minor Planet Bulletin. 36 (3): 127–128. Bibcode:2009MPBu...36..127B. ISSN 1052-8091. Retrieved 23 January 2016. 
  6. ^ Hanus, J.; Broz, M.; Durech, J.; Warner, B. D.; Brinsfield, J.; Durkee, R.; et al. (November 2013). "An anisotropic distribution of spin vectors in asteroid families". Astronomy and Astrophysics. 559: 19. arXiv:1309.4296free to read. Bibcode:2013A&A...559A.134H. doi:10.1051/0004-6361/201321993. Retrieved 23 January 2016. 
  7. ^ Veres, Peter; Jedicke, Robert; Fitzsimmons, Alan; Denneau, Larry; Granvik, Mikael; Bolin, Bryce; et al. (November 2015). "Absolute magnitudes and slope parameters for 250,000 asteroids observed by Pan-STARRS PS1 - Preliminary results". Icarus. 261: 34–47. arXiv:1506.00762free to read. Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007. Retrieved 26 April 2016. 
  8. ^ a b "4606 Saheki (1987 UM1)". Minor Planet Center. Retrieved 23 January 2016. 
  9. ^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 17 May 2016. 

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