6395 Hilliard

6395 Hilliard, provisional designation 1990 UE1, is a stony Nysian asteroid from the inner regions of the asteroid belt, approximately 4.5 kilometers in diameter.

6395 Hilliard
Discovery [1]
Discovered byY. Kushida
O. Muramatsu
Discovery siteYatsugatake Obs.
Discovery date21 October 1990
Designations
(6395) Hilliard
Named after
Elizabeth and Leslie Hilliard
(Herschel Museum of Astronomy)[2]
1990 UE1 · 1975 VU8
1986 QX5
main-belt · Nysa [3]
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc67.17 yr (24,534 days)
Aphelion2.8975 AU
Perihelion1.9287 AU
2.4131 AU
Eccentricity0.2007
3.75 yr (1,369 days)
50.639°
0° 15m 46.44s / day
Inclination1.4970°
227.68°
179.25°
Physical characteristics
Dimensions4.082±0.080 km[4][5]
4.71 km (calculated)[3]
0.20 (assumed)[3]
0.351±0.018[4][5]
S [3][6]
13.7[4] · 14.0[1][3] · 14.03±0.25[6]

    It was discovered on 21 October 1990, by Japanese astronomers Yoshio Kushida and Osamu Muramatsu at Yatsugatake South Base Observatory, Japan.[7] The asteroid was later named after the British philanthropic couple Elizabeth and Leslie Hilliard, donors of the Herschel Museum of Astronomy.[2]

    Orbit and classification

    Hilliard is a stony member of the Nysa family, a relatively small family named after its namesake 44 Nysa. It orbits the Sun in the inner main-belt at a distance of 1.9–2.9 AU once every 3 years and 9 months (1,369 days). Its orbit has an eccentricity of 0.20 and an inclination of 1° with respect to the ecliptic.[1]

    The asteroid was first found on a precovery image taken at Palomar Observatory in 1949. Its first used observations was taken at Crimea-Nauchnij in 1975, when it was identified as 1975 VU8, extending the body's observation arc by 15 years prior to its official discovery observation at Yatsugatake.[7]

    Physical characteristics

    Pan-STARRS' photometric survey has characterized Hilliard as a common stony S-type asteroid.[6]

    According to the survey carried out by NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Hilliard measures 4.082 kilometers in diameter and its surface has a high albedo of 0.351,[4][5] while the Collaborative Asteroid Lightcurve Link assumes a standard albedo for stony asteroids of 0.20 and calculates a large diameter of 4.71 kilometers with on an absolute magnitude of 14.0, as diameter and albedo (reflectivity) are inversely related to each other.[3]

    Lightcurve

    No rotational lightcurve of Hilliard has been obtained from photometric observations. In 2006, observations at the RHIT in Terre Haute, Indiana, United States, rendered no observable brightness variation.[8] As of 2017, the body's rotation period and shape remain unknown.[3]

    Naming

    This minor planet was named in honor of Elizabeth (1903–2001) and Leslie Hilliard (1905–1997), donors of the Herschel Museum of Astronomy in Bath, England. The museum was formerly the home of astronomer William Herschel, from the garden of which he discovered the planet Uranus in 1781.[2][9] The official naming citation was published on 9 September 1995 (M.P.C. 25655).[10]

    References
    1. "JPL Small-Body Database Browser: 6395 Hilliard (1990 UE1)" (2017-01-26 last obs.). Jet Propulsion Laboratory. Retrieved 4 July 2017.
    2. Schmadel, Lutz D. (2007). "(6395) Hilliard". Dictionary of Minor Planet Names – (6395) Hilliard. Springer Berlin Heidelberg. p. 529. doi:10.1007/978-3-540-29925-7_5839. ISBN 978-3-540-00238-3.
    3. "LCDB Data for (6395) Hilliard". Asteroid Lightcurve Database (LCDB). Retrieved 29 April 2017.
    4. 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.
    5. 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. Retrieved 29 April 2017.
    6. 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. Retrieved 29 April 2017.
    7. "6395 Hilliard (1990 UE1)". Minor Planet Center. Retrieved 29 April 2017.
    8. Lecrone, Crystal; Duncan, Allison; Hudson, Erin; Johnson, Jama; Mulvihill, Alex; Reichert, Chris; et al. (September 2006). "2005-2006 fall observing campaign at Rose-Hulman Institute of Technology". The Minor Planet Bulletin. 33 (3): 66–67. Bibcode:2006MPBu...33...66L. ISSN 1052-8091. Retrieved 29 April 2017.
    9. "Elizabeth Hilliard – Obiturary". The Independent. 13 June 2001. Retrieved 29 April 2017.
    10. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 29 April 2017.

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