(415029) 2011 UL21
| Discovery[1] | |
|---|---|
| Discovered by |
Catalina Sky Survey (703) 0.68-m Schmidt + CCD |
| Discovery date | 17 October 2011 |
| Designations | |
| MPC designation | 2011 UL21 |
|
Apollo NEO, PHA[2] | |
| Orbital characteristics[2] | |
| Epoch 13 January 2016 (JD 2457400.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 9379 days (25.68 yr) |
| Aphelion | 3.5091 AU (524.95 Gm) (Q) |
| Perihelion | 0.73606 AU (110.113 Gm) (q) |
| 2.1226 AU (317.54 Gm) (a) | |
| Eccentricity | 0.65323 (e) |
| 3.09 yr (1129.5 d) | |
| 110.19° (M) | |
| 0° 19m 7.392s / day (n) | |
| Inclination | 34.845° (i) |
| 275.60° (Ω) | |
| 284.74° (ω) | |
| Earth MOID | 0.0185982 AU (2.78225 Gm) |
| Jupiter MOID | 2.70453 AU (404.592 Gm) |
| Jupiter Tisserand parameter | 3.245 |
| Physical characteristics | |
| Dimensions | ~2500 meters[3] |
| Mass | 2.1×1013 kg (assumed)[3] |
| 15.8[2] | |
|
| |
(415029) 2011 UL21 (provisionally known as 2011 UL21) is an Apollo class potentially hazardous asteroid (PHA) discovered on October 17, 2011 by the Catalina Sky Survey project.[1] The asteroid is estimated to have a diameter of 2.5 kilometres (1.6 mi). It was rated at Torino Scale 1 on October 27, 2011 with an observation arc of 9.6 days.[4] (415029) 2011 UL21 briefly had about a 1 in a million chance of impacting in 2029.[5] Its cumulative impact probability was dropped to 1 in 71 million by 2 November 2011 with an observation arc of 15 days. It was removed from the Sentry Risk Table on 4 November 2011 when all impact scenarios for the next 100 years or more were ruled out.[6] During 2029, the closest approach to Earth is 1.6AU. Palomar Observatory precovery images from 1989 and 1990 have extended the observation arc to 22 years.[7] Its next notable close approach to the Earth will be on June 27, 2024 at a distance of 0.044 AU (6,600,000 km; 4,100,000 mi).[8]
With an absolute magnitude (H) of 15.8,[2] it is potentially the largest/brightest potentially hazardous asteroid detected since (242450) 2004 QY2.[9] The next largest PHA (based on absolute magnitude) discovered in 2011 is 2011 WO41 with an absolute magnitude of 16.8.[9]
References
- 1 2 "MPEC 2011-U39 : 2011 UL21". IAU Minor Planet Center. 2011-10-28. Retrieved November 1, 2011.
- 1 2 3 4 "JPL Small-Body Database Browser: (2011 UL21)". Jet Propulsion Laboratory. Retrieved 8 April 2016.
2012-04-18 last obs (arc=22 years)
- 1 2 "Earth Impact Risk Summary: 2011 UL21". NASA/JPL Near-Earth Object Program Office. Retrieved November 1, 2011. (Wayback Machine)
- ↑ "Observations of small Solar-System bodies". hohmanntransfer. 2011-10-27. Retrieved 2013-09-04. (1.5e-06 = 1 in 667,000 chance)
- ↑ David Morrison (October 26, 2011). "Should we be concerned about 2011 UL21". NASA Ask An Astrobiologist. Retrieved 2011-11-06.
- ↑ "Date/Time Removed". NASA/JPL Near-Earth Object Program Office. Retrieved 2011-11-06.
- ↑ "2011 UL21 Orbit". Minor Planet Center. Retrieved 2012-05-17.
2012 04 18 (arc=22 years)
- ↑ "JPL Close-Approach Data: (2011 UL21)". Retrieved 2012-05-17.
2012-04-18 last obs (arc=22 years)
- 1 2 "JPL Small-Body Database Search Engine: PHAs and H < 17 (mag)". JPL Solar System Dynamics. Retrieved 2011-11-20.