(162421) 2000 ET70

Near-Earth asteroid October 2019 yes (162421) 2000 ET 70 #FFC2E0 LINEAR Lincoln Lab's ETS 8 March 2000 (162421) 2000 ET 70 NEOPHAAten 4 September 2017 (JD 2458000.5) 0 37.17 yr (13,575 d) 1.0638 AU 0.8295 AU 0.9467 AU 0.1237 0.92 yr (336 days) 129.36° 1.0701 ms / day 22.323° 331.16° 46.103° 0.0316 AU12.3 LD 2.6×2.2×2.1 km2.9×2.2×1.5 km2.0 0.2 km2.10 0.07 km2.26 0.11 km 8.94 0.04 h8.9444 0.0008 h8.947 0.001 hlightcurve-plot-Oey8.96 0.01 h 0.018 0.0020.065 0.05 Xk 18.018.2 (162421) 2000 ET 70 is a dark, elongated and oblate asteroid, classified as near-Earth object and potentially hazardous asteroid of the Aten group, approximately 2.2 kilometers in diameter. It was discovered on 8 March 2000, by astronomers of the Lincoln Near-Earth Asteroid Research at the Lincoln Laboratory's Experimental Test Site near Socorro, New Mexico. The body has a notably low albedo, and its shape resembles that of a "clenched fist". Orbit and classification 2000 ET 70 orbits the Sun at a distance of 0.8–1.1 AU once every 11 months (336 days; semi-major axis of 0.95 AU). Its orbit has an eccentricity of 0.12 and an inclination of 22° with respect to the ecliptic. A first precovery was found in the Digitized Sky Survey from images taken at ESO's La Silla Observatory in February 1977. The body's observation arc begins with its official discovery observation at Socorro in March 2000. Close approaches The asteroid has an Earth minimum orbital intersection distance of 0.0316 AU km on off 3 which translates into 12.3 lunar distances. In February 2012, it was observed by radar during a close approach (0.045 AU) at the Arecibo and Goldstone observatories. The observations allowed to model the body's spin period and rotation, as well as its shape (see below). Physical characteristics 2000 ET 70 has been characterized as a Xk-subtype, which transitions between the X- and K-type asteroids. Rotation period, pole, and shape During its close approach in February 2012, a rotational lightcurve of 2000 ET 70 was obtained from photometric observations by a collaboration of astronomers from Uruguay, Australia, and the United States. Analysis of the lightcurve gave a period of 8.947 hours with a brightness amplitude of 0.60 magnitude (U=3-).lightcurve-plot-Oey Radar observations at Arecibo and Goldstone showed that the asteroid spins in a retrograde manner with a rotation period of 8.96 hours. It is likely a principal axis rotator, i.e., not tumbling. Shape modelling by two independent teams gave sidereal periods of 8.96 and 8.944 hours, respectively. A spin axis of (80.0°, −50.0°) in ecliptic coordinates was determined. The observations also revealed that the asteroid has an elongated oblate shape, resembling a "clenched fist". Its surface exhibits multiple kilometer scale ridges and concavities. Diameter and albedo According to shape modeling of radar observations, the asteroid's overall dimensions are 2.6×2.2×2.1 kilometers. Based on an absolute magnitude of 18.2, this results in a notably low albedo of 0.018. More recent modeling combining radar, photometric, and infrared data gave and even more elongated shape of 2.9×2.2×1.5 kilometers. These authors argue that the absolute magnitude value is incorrect and report a geometric albedo of 0.09. 2000 ET 70's mean-diameter measures between 2.0 and 2.26 kilometers and its surface has an albedo between 0.018 and 0.09. The Collaborative Asteroid Lightcurve Link adopts an albedo of 0.018 and a diameter of 2.26 kilometers based on an absolute magnitude of 18.2. Numbering and naming This minor planet was numbered on 26 September 2007, after its orbital parameters had been sufficiently determined (M.P.C. 60670). As of 2018, it has not been named. Notes lightcurve-plot-Oey Lightcurve plot of (162421) 2000 ET 70, by Julian Oey (2012) at Blue Mountains Observatory (Kingsgrove Observatory; E19). Lightcurve period 8.970 0.004 hours. Note: additional photometric data from other observatories gave a refined period of 8.947 hours. Summary figures at the LCDB References 30em 2014-04-20 last obs. JPL Small-Body Database Browser: 162421 (2000 ET70) https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2162421 Jet Propulsion Laboratory 28 November 2017 162421 (2000 ET70) Minor Planet Center https://www.minorplanetcenter.net/db_search/show_object?object_id=162421 28 November 2017 MPC/MPO/MPS Archive Minor Planet Center https://www.minorplanetcenter.net/iau/ECS/MPCArchive/MPCArchive_TBL.html 28 November 2017 162421 28 November 2017 6 Shantanu Naidu J. L. Margot P. A. Taylor M. C. Nolan M. Brozovic L. A. M. Benner J. D. Giorgini E. S. Howell Ellen Howell M. W. Busch C. Magri October 2012 Radar Observations and Shape Modeling of Near-Earth Asteroid (162421) 2000 ET70 American Astronomical Society 302.06 2012DPS....4430206N 6 Shantanu P. Naidu Jean-Luc Margot Michael W. Busch Patrick A. Taylor Michael C. Nolan Marina Brozovic Lance A. M. Benner Jon D. Giorgini Christopher Magri September 2013 Radar imaging and physical characterization of near-Earth Asteroid (162421) 2000 ET70 Icarus 226 1 323–335 2013Icar..226..323N 10.1016/j.icarus.2013.05.025 1301.6655 6 Sean E. Marshall Ellen S. Howell Ellen Howell Christopher Magri Ronald J. Vervack Donald B. Campbell Yanga R. Fernández Michael C. Nolan Jenna L. Crowell Michael D. Hicks Kenneth J. Lawrence Patrick A. Taylor August 2017 Thermal properties and an improved shape model for near-Earth asteroid (162421) 2000 ET70 Icarus 292 22–35 2017Icar..292...22M 10.1016/j.icarus.2017.03.028 1610.04653 6 Eduardo Manuel Alvarez Julian Oey Xianming L. Han Orry R. Heffner Adam W. Kidd Bradley J. Magnetta Frederick W. Rastede July 2012 Period Determination for NEA (162421) 2000 ET70 The Minor Planet Bulletin 39 3 170 1052-8091 2012MPBu...39..170A External links Imaging near-Earth asteroid (162421) 2000 ET70 Asteroid (162421) 2000 ET70 3D model Asteroid Lightcurve Database (LCDB), query form (info https://web.archive.org/web/20171216050541/http://www.minorplanet.info/lightcurvedatabase.html 16 December 2017 ) Asteroids and comets rotation curves, CdR https://web.archive.org/web/20160729213840/http://obswww.unige.ch/~behrend/page_cou.html 29 July 2016 – Observatoire de Genève, Raoul Behrend 162421 162421 2000ET70 162421 (162421) 2000 ET 70 162421 162421 162421 162421 20000308