(66391) 1999 KW4

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(66391) 1999 KW4
1999 KW4 animated.gif
Simulated animation of 1999 KW4's rotation and moon.
Discovery
Discovered by LINEAR
Discovery date May 20, 1999
Designations
none
Minor planet category Aten asteroid,
Mercury-crosser asteroid,
Venus-crosser asteroid
Orbital characteristics
Epoch July 14, 2004 (JD 2453200.5)
Aphelion 1.084 AU (162.228 Gm)
Perihelion 0.200 AU (29.943 Gm)
0.642 AU (96.085 Gm)
Eccentricity 0.688
188.017 d (0.51 a)
37.16 km/s
168.533°
Inclination 38.890°
244.934°
192.597°
Physical characteristics
Dimensions 1.5 x 1.5 x 1.34 km (primary)
Mass 2.4×1012 kg
Mean density
2.0 g/cm³
0–0.000 36 m/s² (variable)
0.000 72 km/s
0.1152 d
Albedo 0.15
Temperature 250–600 K
16.5

(66391) 1999 KW4 (also written (66391) 1999 KW4) is an Aten and Mercury-crosser asteroid discovered by LINEAR in 1999.

1999 KW4 has a moon orbiting it. The moon, designated S/2001 (66391) 1 or "1999 KW4 Beta", is ~360 m in diameter, and orbits 1999 KW4 'Alpha' in 0.758 d (16 hours) at a distance of 2.6 km. The presence of a companion was suggested by photometric observations made June 19–27, 2000 by Petr Pravec and Lenka Šarounová at Observatoř Ondřejov (Ondřejov Observatory) and was confirmed by radar observations from Arecibo Observatory from May 21–23, 2001 by Lance A. M. Benner, Steven J. Ostro, Jon D. Giorgini, Raymond F. Jurgens, Jean-Luc Margot and Michael C. Nolan, announced on May 23, 2001.

The shapes of the two bodies and their dynamics are complex.[1] Among other bizarre properties, the equatorial regions of Alpha are very close to breakup: raising a particle a meter above the surface would put it into orbit around the object.

On May 25, 2036 it will pass 0.0155 AU (2,320,000 km; 1,440,000 mi) from Earth.[2]

References[edit]

  1. ^ NASA Jet Propulsion Laboratory Asteroid Radar Research, retrieved May 3, 2007
  2. ^ "JPL Close-Approach Data: 66391 (1999 KW4)". 2013-05-09 last obs (arc=14.9 yr). Retrieved 2014-03-02.