Discovery[1] | |
---|---|
Discovered by | MLS |
Discovery site | Mount Lemmon Obs. |
Discovery date | 2 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 arc | 9.54 yr (3,485 days) |
Aphelion | 1.3548 AU |
Perihelion | 0.8260 AU |
1.0904 AU | |
Eccentricity | 0.24248 |
1.14 yr (415.9 days) | |
337.252° | |
Inclination | 3.3735° |
339.890° | |
273.568° | |
Earth MOID | 0.000630 AU (94,200 km) |
Jupiter MOID | 3.681 AU |
Physical characteristics | |
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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