(444004) 2004 AS₁

(444004) 2004 AS₁, provisional designation 2004 AS₁, and also known by the temporary name AL00667,[2] is a sub-kilometer asteroid, classified as near-Earth object and potentially hazardous asteroid of the Apollo group, approximately 300 meters in diameter.

(444004) 2004 AS₁

Discovery [1]
Discovered by	LINEAR
Discovery site	Lincoln Lab's ETS
Discovery date	13 January 2004
Designations
MPC designation	(444004) 2004 AS1
Alternative designations	2004 AS1 · AL00667 [2]
Minor planet category	NEO · Apollo · PHA [1][3]
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc	11.68 yr (4,265 days)
Aphelion	1.2573 AU
Perihelion	0.8838 AU
Semi-major axis	1.0706 AU
Eccentricity	0.1744
Orbital period	1.11 yr (405 days)
Mean anomaly	21.337°
Mean motion	0° 53^m 23.28^s / day
Inclination	17.215°
Longitude of ascending node	322.56°
Argument of perihelion	262.07°
Earth MOID	0.0240 AU (9.3 LD)
Physical characteristics
Mean diameter	240 m (est. at 0.20)[4] 480 m (est. at 0.05)[4]
Absolute magnitude (H)	20.5[1]

It was discovered on 13 January 2004, by astronomers of the LINEAR program at the Lincoln Laboratory's Experimental Test Site near Socorro, New Mexico, in the United States.[3]

Description

Based on the asteroids brightness and assumed proximity to Earth, the asteroid was originally estimated to be only 30 meters in diameter.[5]

Orbit and classification

2004 AS₁ orbits the Sun at a distance of 0.88–1.26 AU once every 13 months (405 days; semi-major axis of 1.07 AU). Its orbit has an eccentricity of 0.17 and an inclination of 17° with respect to the ecliptic.[1] The body's observation arc begins with its official discovery observation at Socorro in January 2004.[3]

Close approaches

Although rather ordinary, it caused some controversy in astronomical circles due to initial projections posted on the web by the Minor Planet Center (MPC) suggesting an imminent collision with Earth on or about January 15 with a likelihood of 1:4.[2] These projections came from very early observations, and turned out to be inaccurate (which is an ordinary occurrence in astronomy, as new observations refine the projected path of an object). In fact, the poster at the MPC had not realised that the data he had posted was essentially an impact prediction.

The asteroid passed Earth on 16 February 2004 at a distance of 0.08539 AU (12,774,000 km; 7,937,000 mi)[1](or 33 times the distance from Earth to the Moon), posing no threat. It is an Apollo asteroid, with perihelion at 0.88 AU, a rather low eccentricity of 0.17, an inclination of 17° and an orbital period of 1.11 years.[1]

Diameter and albedo

Based on a generic magnitude-to-diameter conversion, 2004 AS₁ measures between 240 and 480 meters in diameter, for a measured absolute magnitude of 20.5, and an assumed albedo of 0.20 and 0.05, which corresponds to a body with a stony and carbonaceous composition, respectively.[4]

References

1. "JPL Small-Body Database Browser: 444004 (2004 AS1)" (2015-09-17 last obs.). Jet Propulsion Laboratory. Retrieved 8 February 2018.
2. "2004 AS1 (When initial predictions go wrong...)". Great Shefford Observatory. Retrieved 25 February 2014. archive
3. "444004 (2004 AS1)". Minor Planet Center. Retrieved 8 February 2018.
4. "Asteroid Size Estimator". CNEOS NASA/JPL. Retrieved 8 February 2018.
5. "Earth almost put on impact alert". BBC News. 24 February 2004. Retrieved 8 February 2018.

External links

• List of the Potentially Hazardous Asteroids (PHAs), Minor Planet Center
• (444004) 2004 AS1 at NeoDyS-2, Near Earth Objects—Dynamic Site
  • Ephemeris · Obs prediction · Orbital info · MOID · Proper elements · Obs info · Close · Physical info · NEOCC
• (444004) 2004 AS1 at ESA–space situational awareness
  • Ephemerides · Observations · Orbit · Physical Properties · Summary
• (444004) 2004 AS1 at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit diagram · Orbital elements · Physical parameters