(9928) 1981 WE9

Asteroid yes (9928) 1981 WE 9 #D6D6D6 16 November 1981 Perth Obs. Perth Obs. (9928) 1981 WE 9 1971 TJ 11993 FC 43 main-beltFlora 4 September 2017 (JD 2458000.5) 0 65.74 yr (24,012 days) 2.6101 AU 1.8246 AU 2.2174 AU 0.1771 3.30 yr (1,206 days) 340.29° 0.2985 ms / day 2.8472° 179.45° 176.04° 2.441 0.327 km2.938 0.660 km3.00 0.42 km3.11 km (calculated) 5.547 0.005 h18.310 0.0034 h18.3980 0.0034 h 0.24 (assumed)0.283 0.1520.3557 0.22890.428 0.109 S 14.414.6014.7 (9928) 1981 WE 9 is a stony Florian asteroid from the inner regions of the asteroid belt, approximately 3 kilometers in diameter. It was discovered on 16 November 1981, by astronomers at Perth Observatory in Bickley, Australia. Orbit and classification thumb|left|200px|Orbit of 1981 WE 9 (blue), with the inner planets and Jupiter The stony S-type asteroid is a member of the Flora family, one of the largest groups of asteroids in the main-belt. It orbits the Sun at a distance of 1.8–2.6 AU once every 3 years and 4 months (1,206 days). Its orbit has an eccentricity of 0.18 and an inclination of 3° with respect to the ecliptic. A first precovery was taken at Palomar in 1951, extending the body's observation arc by 30 years prior to its official discovery observation at Bickley. Physical characteristics In December 2014, astronomer Maurice Clark obtained a rotational lightcurve from photometric observations at Preston Gott Observatory. Lightcurve analysis gave an ambiguous rotation period of 18.3980 hours with a brightness variation of 0.41 magnitude, suggesting a non-spheroidal shape (U=2+). The alternative period solution is 9.14 hours with an amplitude of 0.32 magnitude. The results supersede a previously obtained period of 5.547 hours (U=2). Diameter and albedo According to the survey carried out by NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, the asteroid measures between 2.44 and 3.00 kilometers in diameter, and its surface has an albedo between 0.283 and 0.428. The Collaborative Asteroid Lightcurve Link assumes an intermediate albedo of 0.24 – derived from 8 Flora, the largest member and namesake of this asteroid family – and calculates a diameter of 3.11 kilometers with an absolute magnitude of 14.7. Numbering and naming This minor planet was numbered by the Minor Planet Center on 2 February 1999. As of 2018, it has not been named. References 30em 2017-05-05 last obs. JPL Small-Body Database Browser: 9928 (1981 WE9) https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2009928 Jet Propulsion Laboratory 26 May 2017 9928 (1981 WE9) Minor Planet Center https://www.minorplanetcenter.net/db_search/show_object?object_id=9928 17 March 2017 MPC/MPO/MPS Archive Minor Planet Center https://www.minorplanetcenter.net/iau/ECS/MPCArchive/MPCArchive_TBL.html 24 February 2018 9928 17 March 2017 6 A. Mainzer T. Grav J. Masiero E. Hand J. Bauer D. Tholen R. S. McMillan T. Spahr R. M. Cutri E. Wright J. Watkins W. Mo C. Maleszewski November 2011 NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results The Astrophysical Journal 741 2 25 2011ApJ...741...90M 10.1088/0004-637X/741/2/90 1109.6407 6 Joseph R. Masiero A. K. Mainzer T. Grav J. M. Bauer R. M. Cutri C. Nugent M. S. Cabrera November 2012 Preliminary Analysis of WISE/NEOWISE 3-Band Cryogenic and Post-cryogenic Observations of Main Belt Asteroids The Astrophysical Journal Letters 759 1 5 2012ApJ...759L...8M 10.1088/2041-8205/759/1/L8 1209.5794 6 C. R. Nugent A. Mainzer J. Masiero J. Bauer R. M. Cutri T. Grav E. Kramer S. Sonnett R. Stevenson E. L. Wright December 2015 NEOWISE Reactivation Mission Year One: Preliminary Asteroid Diameters and Albedos The Astrophysical Journal 814 2 13 2015ApJ...814..117N 10.1088/0004-637X/814/2/117 1509.02522 Clark, Maurice June 2008 Asteroid Lightcurves from the Chiro Observatory The Minor Planet Bulletin 35 2 42–43 1052-8091 2008MPBu...35...42C Clark, Maurice July 2015 Asteroid Photometry from the Preston Gott Observatory The Minor Planet Bulletin 42 3 163–166 1052-8091 2015MPBu...42..163C External links Asteroid Lightcurve Database (LCDB), query form (info https://web.archive.org/web/20171216050541/http://www.minorplanet.info/lightcurvedatabase.html 2017-12-16 ) Dictionary of Minor Planet Names, Google books Asteroids and comets rotation curves, CdR https://web.archive.org/web/20160729213840/http://obswww.unige.ch/~behrend/page_cou.html 2016-07-29 – Observatoire de Genève, Raoul Behrend Discovery Circumstances: Numbered Minor Planets (5001)-(10000) – Minor Planet Center 9928 (1981 WE9) 2009928 9927 Tyutchev 9928 (9928) 1981 WE 9 9929 McConnell 009928 009928 19811116