(391211) 2006 HZ51

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(391211) 2006 HZ51
Discovery [1]
Discovered by Catalina Sky Srvy.
Discovery site Mount Lemmon Obs.
Discovery date 27 April 2006
MPC designation (391211) 2006 HZ51
2006 HZ51
Amor · NEO · PHA[1][2]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc 16.10 yr (5,882 days)
Aphelion 2.7511 AU
Perihelion 1.0438 AU
1.8974 AU
Eccentricity 0.4499
2.61 yr (955 days)
0° 22m 37.56s / day
Inclination 12.412°
Earth MOID 0.0354 AU (13.8 LD)
Physical characteristics
Mean diameter
0.412±0.089 km[3]
0.8 km (estimate)[4]

(391211) 2006 HZ51 is a bright, sub-kilometer asteroid on an eccentric orbit, classified as a near-Earth object and a potentially hazardous asteroid of the Amor group. It was discovered on 27 April 2006, by astronomers of the Catalina Sky Survey conducted at Mount Lemmon Observatory, Arizona, United States.[2] During preliminary observations, it was thought to have a small chance of impacting Earth in 2008.[4] The asteroid measures approximately half a kilometer in diameter and has an exceptionally high albedo.[3]

Orbit and classification[edit]

2006 HZ51 is an Amor asteroid – a subgroup of near-Earth asteroids that approach the orbit of Earth from beyond, but do not cross it.[1][2]

It orbits the Sun at a distance of 1.04–2.75 AU once every 2 years and 7 months (955 days; semi-major axis of 1.90 AU). Its orbit has an eccentricity of 0.45 and an inclination of 12° with respect to the ecliptic.[1] The body's observation arc begins with a precovery taken by NEAT at Palomar Observatory in October 2001.[2] With an aphelion of 2.75 AU, and typical for members of the Amor group, this asteroid is also a Mars-crosser, crossing the orbit of the Red Planet at 1.666 AU.

Close approaches[edit]

2006 HZ51 has a minimum orbital intersection distance (MOID) with Earth of 5,290,000 km (0.035385 AU), which translates into 13.8 lunar distances.[1]

This makes it a potentially hazardous asteroid, a body with a threatening close approach to the Earth, due to its low MOID and large size (absolute magnitude of 18.5). Such asteroids are defined to have an absolute magnitude of 22 or brighter – which generically corresponds to a diameter of approximately 140 meters – and a MOID that is smaller than 0.05 AU or 19.5 LD.

Based on a short observation arc of only 1.1 days, it was originally thought to have a 1 in 6 million chance of hitting Earth on 21 June 2008.[4] Further refinement of the orbit quickly eliminated the risk. The preliminary 2-day orbit solution on 28 April 2006 was at first thought to have a period of 7 years and a perihelion of approximately 1.1 AU (MPEC 2006-H58).

Physical characteristics[edit]

Diameter and albedo[edit]

According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, 2006 HZ51 measures 412 meters in diameter and its surface has an exceptionally high albedo of 0.415.[3] Other source give an estimated diameter of 800 meters.[4]

Rotation period[edit]

As of 2018, n rotational lightcurve of 2006 HZ51 has been obtained from photometric observations. The body's rotation period, pole and shape remains unknown.[1][5]


This minor planet has not yet been named.[2]


  1. ^ a b c d e f g h "JPL Small-Body Database Browser: 391211 (2006 HZ51)" (2017-11-21 last obs.). Jet Propulsion Laboratory. Retrieved 30 January 2018. 
  2. ^ a b c d e "391211 (2006 HZ51)". Minor Planet Center. Retrieved 30 January 2018. 
  3. ^ a b c d Nugent, C. R.; Mainzer, A.; Masiero, J.; Bauer, J.; Cutri, R. M.; Grav, T.; et al. (December 2015). "NEOWISE Reactivation Mission Year One: Preliminary Asteroid Diameters and Albedos". The Astrophysical Journal. 814 (2): 13. arXiv:1509.02522Freely accessible. Bibcode:2015ApJ...814..117N. doi:10.1088/0004-637X/814/2/117. Retrieved 30 January 2018. 
  4. ^ a b c d "Big new asteroid has slim chance of hitting Earth". New Scientist. 2 May 2006. Retrieved 30 January 2018. 
  5. ^ "LCDB Data for (391211)". Asteroid Lightcurve Database (LCDB). Retrieved 30 January 2018. 

External links[edit]