(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.
| Discovery[1][2] | |
|---|---|
| Discovered by | Mt. Lemmon Survey |
| Discovery date | 12 January 2008 |
| Designations | |
Designation |
|
| Orbital characteristics[2] | |
| Epoch 18 April 2013 (JD 2456400.5) | |
| Uncertainty parameter 1[2] | |
| Aphelion | 1.808 AU (Q) |
| Perihelion | 0.9352 AU (q) |
| 1.372 AU (a) | |
| Eccentricity | 0.3182 |
| 1.61 yr | |
| 100.4° (M) | |
| Inclination | 8.359° |
| 73.98° | |
| 350.0° | |
| Physical characteristics | |
| Dimensions | ~310 meters (1,020 ft)[3] |
| Mass | 4.1×1010 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]
- ^ a b “MPEC 2008-D33”. IAU Minor Planet Center. 25 February 2008. Retrieved 28 August 2013. (K08AB2O)
- ^ 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.
- ^ 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)
- ^ “MPEC 2013-E32 : 2013 EM20”. IAU Minor Planet Center. 8 March 2013. Retrieved 28 August 2013. (K13E20M)
- ^ “Date/Time Removed”. NASA/JPL Near-Earth Object Program Office. Archived from the original on 2 June 2002. Retrieved 28 August 2013.
- ^ Horizons output. “Horizon Online Ephemeris System”. Retrieved 28 August 2013. (Geocentric Solution)
- (517103) 2013 EM20 at NeoDyS-2, Near Earth Objects—Dynamic Site
- (517103) 2013 EM20 at ESA–space situational awareness
- (517103) 2013 EM20 at the JPL Small-Body Database
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