(721708) 2004 BX159

(721708) 2004 BX₁₅₉ is an asteroid from the central region of the asteroid belt, approximately 1.2 kilometers in diameter. It was first observed at Paranal Observatory in the Atacama desert of Chile on 20 January 2004.^[2] 2004 BX₁₅₉ missed the virtual impactor date of 29 August 2009.^[5] The asteroid was removed from the Sentry Risk Table in April 2014^[6] as a result of precovery images establishing it is a harmless main belt asteroid.

(721708) 2004 BX₁₅₉

Discovery[1][2]
Discovered by	Paranal Obs.
Discovery site	Paranal Obs.
Discovery date	20 January 2004 (discovery: first observation only)
Designations
MPC designation	2004 BX159
Minor planet category	main-belt[1][2] · (middle)
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc	19.97 yr (7,293 days)
Earliest precovery date	14 July 1997
Aphelion	2.8997 AU
Perihelion	2.1632 AU
Semi-major axis	2.5315 AU
Eccentricity	0.1455
Orbital period (sidereal)	4.03 yr (1,471 days)
Mean anomaly	355.95°
Mean motion	0° 14m 40.92s / day
Inclination	4.0931°
Longitude of ascending node	159.75°
Argument of perihelion	153.29°
Physical characteristics
Dimensions	1.2 km (estimate)[3] 1.8 km (est. at 0.10)[4]
Absolute magnitude (H)	16.9[1]

Description

2004 BX₁₅₉ orbits the Sun in the central main-belt at a distance of 2.2–2.9 AU once every 4.03 years (1,471 days). Its orbit has an eccentricity of 0.15 and an inclination of 4° with respect to the ecliptic.^[1]

After discovery, it was thought to be a Mars-crossing asteroid because of its poorly known orbit, and was listed on the Sentry Risk Table as a possible impactor.^[5] With an observation arc of 3 days and only 8 observations, perihelion was determined to be 1.5±3 astronomical units (AU).^[7]

Precovery observations in archival data of the Canada-France-Hawaii Telescope on Mauna Kea were identified in early 2014, resulting in a dramatic improvement of the orbital accuracy, sufficient to recognize the object as a regular main belt asteroid, not posing any danger to Earth.^[1]

The body was subsequently linked by the Minor Planet Center with additional observations reported since 1997. It has now a well-established orbit, observed over decades, with the lowest possible uncertainty of 0.^[1]

It is even known that 2004 BX₁₅₉ passed 0.0036 AU (540,000 km; 330,000 mi) from asteroid 3 Juno on 18 September 1961.^[1]

See also

• 2010 GZ60