2011 ES4

2011 ES4
Discovery[1]
Discovered byMLS
Discovery siteMount Lemmon Obs.
Discovery date2 March 2011
(first observation only)
Designations
2011 ES4
P1154IU (NEOCP 2020)[2]
Orbital characteristics[3]
Epoch 31 May 2020 (JD 2459000.5)
Uncertainty parameter 1
Observation arc9.54 yr (3,485 days)
Aphelion1.3548 AU
Perihelion0.8260 AU
1.0904 AU
Eccentricity0.24248
1.14 yr (415.9 days)
337.252°
Inclination3.3735°
339.890°
273.568°
Earth MOID0.000630 AU (94,200 km)
Jupiter MOID3.681 AU
Physical characteristics
  • 22–49 m (CNEOS)
  • ~25 m (82 ft)[4]
25.4[3]

2011 ES4 (also written 2011 ES4) is an Apollo near-Earth asteroid roughly 22–49 meters (72–160 feet) in diameter. It was first observed on 2 March 2011 when the asteroid was about 0.054 AU (8,100,000 km; 5,000,000 mi) from Earth and had a solar elongation of 159 degrees. It passed closest approach to Earth on 13 March 2011.[3] Before the 2020 approach, the asteroid had a short observation arc of 4 days and had not been observed since March 2011. The asteroid was expected to pass within 1 lunar distance of Earth in early September 2020, but did not. There was no risk of a 2020 impact because the line of variation (LOV) did not pass through where Earth would be, and the closest possible 2020 Earth approach was about 0.00047 AU (70,000 km; 44,000 mi).[3] One line of variation showed the asteroid passing closest to Earth on 5 September 2020 at 0.06 AU (9,000,000 km; 5,600,000 mi) with a magnitude of 23, which would place it near the limiting magnitude of even the best automated astronomical surveys.[5]

2011 ES4 was recovered as P1154IU[6][2] on 5 September 2020 at apparent magnitude 18.[7] It passed 0.009886 AU (3.847 LD; 1,478,900 km; 919,000 mi) from Earth on 2 September 2020.[3] With the observation arc being extended to 9 years, it was removed from the Sentry Risk Table on 6 September 2020.

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  2. ^ a b Cite error: The named reference projectpluto was invoked but never defined (see the help page).
  3. ^ a b c d e f Cite error: The named reference jpldata was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference sentry was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference NEODyS2020-archive was invoked but never defined (see the help page).
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  7. ^ Cite error: The named reference MPEC2020-R18 was invoked but never defined (see the help page).