(517103) 2013 EM20 (also designated 2008 AO112) is an Apollo near-Earth asteroid and potentially hazardous object.[2] It was discovered on 12 January 2008 by the Mount Lemmon Survey at an apparent magnitude of 21 using a 1.5-meter (59 in) reflecting telescope.[1] The asteroid was quickly lost and had an estimated diameter of 310 meters (1,020 ft).[3] On 25 June 2009, with an observation arc of only 1 day in January 2008, the asteroid had a 1 in 4 million chance of impacting Earth on that very day.[3] The virtual impactor had not been eliminated from the Sentry Risk Table by the day of the potential impact.

(517103) 2013 EM20
Discovery[1][2]
Discovered byMt. Lemmon Survey
Discovery date12 January 2008
Designations
Designation
  • 2008 AO112
  • 2013 EM20
Orbital characteristics[2]
Epoch 18 April 2013 (JD 2456400.5)
Uncertainty parameter 1[2]
Aphelion1.808 AU (Q)
Perihelion0.9352 AU (q)
1.372 AU (a)
Eccentricity0.3182
1.61 yr
100.4° (M)
Inclination8.359°
73.98°
350.0°
Physical characteristics
Dimensions~310 meters (1,020 ft)[3]
Mass4.1×1010 kg (assumed)[3]
19.9[2]

The asteroid was recovered on 5 March 2013 as 2013 EM20.[4] Precovery images from 7 April 1997 at Kitt Peak National Observatory were located.[2] It was removed from the Sentry Risk Table on 30 March 2013.[5] It is now known that on 25 June 2009 the asteroid was 1.45 AU from Earth.[6]

References

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  1. ^ a b "MPEC 2008-D33". IAU Minor Planet Center. 25 February 2008. Retrieved 28 August 2013. (K08AB2O)
  2. ^ a b c d e f g "JPL Small-Body Database Browser: (2013 EM20 = 2008 AO112)" (last observation: 2013-05-15; arc: 16.1 years). Jet Propulsion Laboratory. Retrieved 28 August 2013.
  3. ^ a b c d "Earth Impact Risk Summary: 2008 AO112". Wayback Machine: NASA/JPL Near-Earth Object Program Office. 25 June 2009. Archived from the original on 25 June 2009. Retrieved 28 August 2013. (2.5e-07 = 1 in 4,000,000 chance)
  4. ^ "MPEC 2013-E32 : 2013 EM20". IAU Minor Planet Center. 8 March 2013. Retrieved 28 August 2013. (K13E20M)
  5. ^ "Date/Time Removed". NASA/JPL Near-Earth Object Program Office. Archived from the original on 2 June 2002. Retrieved 28 August 2013.
  6. ^ Horizons output. "Horizon Online Ephemeris System". Retrieved 28 August 2013. (Geocentric Solution)
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