7776 Takeishi

7776 Takeishi, provisional designation 1993 BF, is a background asteroid from the inner regions of the asteroid belt, approximately 6 kilometers (4 miles) in diameter. It was discovered on 20 January 1993, by Japanese astronomer Takeshi Urata at the Nihondaira Observatory in Japan.[1] The assumed S-type asteroid has a rotation period of 8.9 hours.[3] It was named after Japanese amateur astronomer Masanori Takeishi.[1]

7776 Takeishi
Discovery [1]
Discovered byT. Urata
Discovery siteNihondaira Obs.
Discovery date20 January 1993
Designations
(7776) Takeishi
Named after
Masanori Takeishi [1]
(Japanese astronomer)
1993 BF · 1981 RJ
1995 UM4
main-belt [1][2] · (inner) [3]
background [4]
Orbital characteristics [2]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc35.66 yr (13,023 d)
Aphelion2.6137 AU
Perihelion1.9042 AU
2.2590 AU
Eccentricity0.1571
3.40 yr (1,240 d)
258.36°
0° 17m 25.08s / day
Inclination9.4908°
309.46°
39.968°
Physical characteristics
Mean diameter
5.99±1.19 km[5]
6.165±0.135 km[6][7]
7.46 km (calculated)[3]
8.65±0.03 h[8]
8.90 h[lower-alpha 1]
0.20 (assumed)[3]
0.29±0.13[5]
0.353±0.051[6][7]
S (assumed)[3]
12.8[7]
13.0[2][3]
13.18±0.27[9]
13.34[5]

    Orbit and classification

    Takeishi is a non-family asteroid from the main belt's background population.[4] It orbits the Sun in the inner asteroid belt at a distance of 1.9–2.6 AU once every 3 years and 5 months (1,240 days; semi-major axis of 2.26 AU). Its orbit has an eccentricity of 0.16 and an inclination of 9° with respect to the ecliptic.[2] The body's observation arc begins with first observations as 1981 RJ at Anderson Mesa Station in September 1981, more than 11 years prior to its official discovery observation.[1]

    Physical characteristics

    Takeishi is an assumed, stony S-type asteroid.[3]

    Rotation period

    Two rotational lightcurves of Takeishi have been obtained from photometric observations by French amateur astronomer Pierre Antonini and Laurent Bernasconi, as well as by American William Koff at the Antelope Hills Observatory (H09) in Colorado. The fragmentary lightcurves gave a poorly determined rotation period of 8.65 and 8.90 hours, respectively. Both showed a minuscule brightness amplitude of 0.05 magnitude (U=1/1).[3][8][lower-alpha 1]

    Diameter and albedo

    According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Takeishi measures between 5.99 and 6.165 kilometers in diameter and its surface has an albedo between 0.29 and 0.353,[5][6][7] while the Collaborative Asteroid Lightcurve Link assumes a standard albedo for a stony asteroid of 0.20, and calculates a diameter of 7.46 kilometers based on an absolute magnitude of 13.0.[3]

    Naming

    This minor planet was named after Japanese amateur astronomer and discoverer of minor planets, Masanori Takeishi (born 1950). Between 1975 and 1993, he was a chief editor of the Japan Astronomical Circular.[1] The official naming citation was published by the Minor Planet Center on 14 December 1997 (M.P.C. 31027).[10]

    Notes
    1. Lightcurve plot of (7776) Takeishi, Antelope Hills Observatory (H09), Robert A. Koff (2011). Quality code of 1. Summary figures at the LCDB.

    References
    1. "7776 Takeishi (1993 BF)". Minor Planet Center. Retrieved 3 May 2018.
    2. "JPL Small-Body Database Browser: 7776 Takeishi (1993 BF)" (2017-05-01 last obs.). Jet Propulsion Laboratory. Retrieved 3 May 2018.
    3. "LCDB Data for (7776) Takeishi". Asteroid Lightcurve Database (LCDB). Retrieved 3 May 2018.
    4. "Asteroid 7776 Takeishi – Proper Elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 29 October 2019.
    5. Nugent, C. R.; Mainzer, A.; Bauer, J.; Cutri, R. M.; Kramer, E. A.; Grav, T.; et al. (September 2016). "NEOWISE Reactivation Mission Year Two: Asteroid Diameters and Albedos". The Astronomical Journal. 152 (3): 12. arXiv:1606.08923. Bibcode:2016AJ....152...63N. doi:10.3847/0004-6256/152/3/63.
    6. Masiero, Joseph R.; Mainzer, A. K.; Grav, T.; Bauer, J. M.; Cutri, R. M.; Dailey, J.; et al. (November 2011). "Main Belt Asteroids with WISE/NEOWISE. I. Preliminary Albedos and Diameters". The Astrophysical Journal. 741 (2): 20. arXiv:1109.4096. Bibcode:2011ApJ...741...68M. doi:10.1088/0004-637X/741/2/68.
    7. 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:1109.6407. Bibcode:2011ApJ...741...90M. doi:10.1088/0004-637X/741/2/90. (catalog)
    8. Behrend, Raoul. "Asteroids and comets rotation curves – (7776) Takeishi". Geneva Observatory. Retrieved 3 May 2018.
    9. 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:1506.00762. Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007.
    10. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 3 May 2018.

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