(415029) 2011 UL₂₁

(415029) 2011 UL₂₁
Discovery[1]
Discovered by	Catalina Sky Srvy.
Discovery site	Catalina Stn.
Discovery date	17 October 2011
Designations
MPC designation	(415029) 2011 UL21
Alternative designations	2011 UL21
Minor planet category	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)
Perihelion	0.73606 AU (110.113 Gm)
Semi-major axis	2.1226 AU (317.54 Gm)
Eccentricity	0.65323
Orbital period (sidereal)	3.09 yr (1129.5 d)
Mean anomaly	110.19°
Mean motion	0° 19m 7.392s / day
Inclination	34.845°
Longitude of ascending node	275.60°
Argument of perihelion	284.74°
Earth MOID	0.0185982 AU (2.78225 Gm)
Physical characteristics
Mean diameter	2.5 km[3]
Mass	2.1×1013 kg (assumed)[3]
Absolute magnitude (H)	15.8[2]

(415029) 2011 UL₂₁, provisional designation 2011 UL₂₁, is an Apollo class potentially hazardous asteroid 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]

Description

2011 UL₂₁ briefly had about a 1 in a million chance of impacting in 2029.[5] Its cumulative impact probability dropped to 1 in 71 million by 2 November 2011 when the observation arc reached 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 1.6 AU. 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 of 15.8,[2] it is one of the brightest and therefore largest potentially hazardous asteroids (PHA) 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]

Chronology of close approaches of large near-Earth objects since 1981 ^(A)

PHA	Date	Approach distance in lunar distances			Abs. mag (H)	Diameter ^(C) (m)	Ref ^(D)
PHA	Date	Nominal ^(B)	Minimum	Maximum	Abs. mag (H)	Diameter ^(C) (m)	Ref ^(D)
(143651) 2003 QO104	1981-05-18	2.761	2.760	2.761	16.0	1333–4306	data
2014 LJ21	1989-08-01	7.034	6.843	7.224	16.0	1333–4306	data
4179 Toutatis	1992-12-08	9.399	9.399	9.399	15.30	2440–2450	data
4179 Toutatis	2004-09-29	4.031	4.031	4.031	15.30	2440–2450	data
(159857) 2004 LJ1	2038-11-16	7.719	7.719	7.719	15.4	1746–4394	data
(4953) 1990 MU	2058-06-05	8.986	8.984	8.988	14.1	3199–10329	data
4179 Toutatis	2069-11-05	7.725	7.724	7.725	15.30	2440–2450	data
(52768) 1998 OR2	2079-04-16	4.611	4.611	4.612	15.8	1462–4721	data
(415029) 2011 UL21	2089-06-25	6.936	6.935	6.938	15.7	1531–4944	data
3200 Phaethon	2093-12-14	7.714	7.709	7.718	14.6	4900–5300	data
(52768) 1998 OR2	2127-04-16	6.536	6.510	6.563	15.8	1462–4721	data
^(A) This list includes near-Earth approaches of less than 10 lunar distances (LD) of objects with H brighter than 16. ^(B) Nominal geocentric distance from the center of Earth to the center of the object (Earth has a radius of approximately 6,400 km). ^(C) Diameter: estimated, theoretical mean-diameter based on H and albedo range between X and Y. ^(D) Reference: data source from the JPL SBDB, with AU converted into LD (1 AU≈390 LD) ^(E) Color codes: unobserved at close approach observed during close approach upcoming approaches

References

"MPEC 2011-U39 : 2011 UL21". IAU Minor Planet Center. 28 October 2011. Retrieved 1 November 2011.
"JPL Small-Body Database Browser: (2011 UL21)". Jet Propulsion Laboratory. Retrieved 8 April 2016. 2012-04-18 last obs (arc=22 years)
"Earth Impact Risk Summary: 2011 UL21". NASA/JPL Near-Earth Object Program Office. Archived from the original on 2 November 2011. Retrieved 1 November 2011.
"Observations of small Solar-System bodies". hohmanntransfer. 27 October 2011. Archived from the original on 29 November 2014. Retrieved 4 September 2013. (1.5e-06 = 1 in 667,000 chance)
David Morrison (26 October 2011). "Should we be concerned about 2011 UL21". NASA Ask An Astrobiologist. Retrieved 6 November 2011.
"Date/Time Removed". NASA/JPL Near-Earth Object Program Office. Retrieved 6 November 2011.
"2011 UL21 Orbit". Minor Planet Center. Retrieved 17 May 2012. 2012 04 18 (arc=22 years)
"JPL Close-Approach Data: (2011 UL21)". Retrieved 17 May 2012. 2012-04-18 last obs (arc=22 years)
"JPL Small-Body Database Search Engine: PHAs and H < 17 (mag)". JPL Solar System Dynamics. Retrieved 20 November 2011.

External links

(415029) 2011 UL21 at NeoDyS-2, Near Earth Objects—Dynamic Site
- Ephemerides · Observation prediction · Orbital info · MOID · Proper elements · Observational info · Close approaches · Physical info · Orbit animation
(415029) 2011 UL21 at ESA–space situational awareness
- Ephemerides · Observations · Orbit · Physical properties · Summary
(415029) 2011 UL21 at the JPL Small-Body Database

This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.

[MPEC2011-U39-1] "MPEC 2011-U39 : 2011 UL21". IAU Minor Planet Center. 28 October 2011. Retrieved 1 November 2011.

[jpl-2] "JPL Small-Body Database Browser: (2011 UL21)". Jet Propulsion Laboratory. Retrieved 8 April 2016. 2012-04-18 last obs (arc=22 years)

[jplneo-3] "Earth Impact Risk Summary: 2011 UL21". NASA/JPL Near-Earth Object Program Office. Archived from the original on 2 November 2011. Retrieved 1 November 2011.

[hohmanntransfer1027-4] "Observations of small Solar-System bodies". hohmanntransfer. 27 October 2011. Archived from the original on 29 November 2014. Retrieved 4 September 2013. (1.5e-06 = 1 in 667,000 chance)

[Morrison-5] David Morrison (26 October 2011). "Should we be concerned about 2011 UL21". NASA Ask An Astrobiologist. Retrieved 6 November 2011.

[removed-6] "Date/Time Removed". NASA/JPL Near-Earth Object Program Office. Retrieved 6 November 2011.

[mpc-7] "2011 UL21 Orbit". Minor Planet Center. Retrieved 17 May 2012. 2012 04 18 (arc=22 years)

[jpl-close-8] "JPL Close-Approach Data: (2011 UL21)". Retrieved 17 May 2012. 2012-04-18 last obs (arc=22 years)

[jpl-search-9] "JPL Small-Body Database Search Engine: PHAs and H < 17 (mag)". JPL Solar System Dynamics. Retrieved 20 November 2011.

2011 in space
2012 »
Space probe launches	Juno (Jupiter orbiter; Aug 2011) GRAIL (mission to the Moon; Sep 2011) Yinghuo-1 (Mars orbiter); Nov 2011) Mars Science Laboratory / Curiosity rover (mission to Mars; Nov 2011) Fobos-Grunt (mission to Mars; Nov 2011)
Selected NEOs	Asteroid close approaches (367789) 2011 AG5 (471240) 2011 BT15 2011 CQ1 2011 ES4 2011 EO40 2011 GA 2009 BD 2011 MD (415029) 2011 UL21 (436724) 2011 UW158 (308635) 2005 YU55 (549948) 2011 WL2 2011 XC2
Exoplanets	82 G. Eridani b c d Gliese 433 b habitability of Gliese 581d Gliese 3634 b HAT-P-32b HAT-P-33b HD 7199 HD 82886 b HD 85512 b HD 98219 b HD 100655 b HD 131496 b HD 137388 b HIP 57274 b c d HR 7722 c Kepler-9d Kepler-10 b c Kepler-11 b c d e f g Kepler-14b Kepler-16b Kepler-18 b c d Kepler-20 b c d e f Kepler-22b Kepler-39b Kepler-70 b c LkCa 15 b MOA-2009-BLG-387Lb PSR J1719−1438 b WASP-39b WASP-43b WASP-44b
Discoveries	UDFj-39546284 GRB 110328A Kronberger 61 WD 0806−661 ULAS J1120+0641 Kerberos (moon) PSR J1719−1438 Uranus trojan 2011 QF99 U1.11 SDSS J102915+172927 2 moons of Jupiter GRB 111209A
Novae	SN 2010lt SN 2011by SN 2011dh SN 2011fe
Comets	P/2011 NO₁ (Elenin) 45P/Honda–Mrkos–Pajdušáková C/2011 W3 (Lovejoy)
Space exploration	MESSENGER (Mercury orbital insertion; Apr 2011) Spirit (end of mission; Mar 2010 / May 2011) Dawn (Vesta orbital insertion; Jul 2011)
Outer space portal Category:2010 in space — Category:2011 in space — Category:2012 in space

(415029) 2011 UL21

Description

References

External links

(415029) 2011 UL₂₁