Goldstone Delay Doppler Radar Images of (153201) 2000 WO107 Suggest a Bi-lobate Contact Binary Object

This sequence of delay doppler radar images of (153201) 2000 WO107 in November 2020 show an object like a bowling pin, a bilobate object or contact binary rotating slowly. It completes half of a revolution between 03:37:15 UTC and 12:13:32 UTC in the top left frames or 2.6 hours. The rotational period is approximately 5.2 hours.

Potentially Hazardous Asteroid (153201) 2000 WO107 passed Earth on November 29, 2020 at 11.19 lunar distances.

(153201) 2000 WO107 was discovered at magnitude 15.8 about 20 years ago, on November 29, 2000 by 704 Lincoln Laboratory ETS, New Mexico or LINEAR at Socorro, New Mexico (MPEC 2000-X08).

With a short perihelion distance of 0.2 au and aphelion distance of 1.6 au, (153201) 2000 WO107 makes close approaches to Mercury, Venus, Earth, and Mars. 

Cosmographia Screenshot showing position of Potentially Hazardous Asteroid (153201) 2000 WO107 at Earth close approach on 2020-Nov-29 05:08 UT and trajectory over previous 20 years from SPICE SPK-ID: 2153201.

(153201) 2000 WO107 is one of 12 Near Earth Asteroids (NEAs) with the largest predicted Yarkovsky drift rates, da/dt = 23.45 ± 10.14 10−4 AU/Myr (Nugent et al. 2012). The Yarkovsky effect is a non-gravitational force that perturbs the orbits of small bodies, including near-Earth asteroids (NEAs). Researchers believe that the Yarkovsky effect is a key mechanism in the process that perturbs the orbits of asteroids in the main belt to near-Earth space.

For (153201) 2000 WO107, the JPL Small Body Database gives a geometric albedo of 0.129 and diameter of 510 meters (Binzel et al. 2004). This diameter is 25 times the size of the Chelyabinsk object. CNEOS NEO Earth Close Approach Tables estimate diameter within the range of 370 to 820 meters assuming an albedo range of 0.25 to 0.05.

(153201) 2000 WO107is classified as a SMASII Class-X spectral object which are generally featureless with a linear spectrum with slight to moderate reddish slope. (Bus et al. 2002 see Table I: Summary of taxonomic classes)

Perihelion distance q = 0.200 au
Near-Earth asteroids (NEAs) have q < 1.3 au, thus, (153201) 2000 WO107 is a NEA.

Semimajor axis = 0.911 au
Aphelion distance Q = 1.623
Objects with these parameters are called Atens or Near-Earth asteroids with orbits similar to that of 2062 Aten (a < 1.0 au; Q > 0.983 au),

Absolute magnitude H = 19.3
Earth MOID = 0.0031 au
(153201) 2000 WO107 is classified as a Potentially Hazardous Asteroids (PHA) or NEA whose Minimum Orbit Intersection Distance (MOID) with the Earth is 0.05 AU or less and whose absolute magnitude (H) is 22.0 or brighter. i.e. MOID <= 0.05 AU, H <= 22.0

0.05 AU = 7479893.53455 km = 19.45 LD or ~ 5 Earth Hill sphere radii

1 Lunar Distance (LD) = 3.844 × 105 km = 384400 km = 0.00257 AU = 238900 miles = the mean distance from the Earth to the Moon

MPEC 2000-X08 : 2000 WO107 (Dec 2000)
MPEC MPEC 2001-V58 : 2000 WO107 (Nov 2001)

Goldstone Asteroid Schedule:
Planning page:

Binzel, Richard P.; Rivkin, Andrew S.; Stuart, J. Scott; Harris, Alan W.; Bus, Schelte J.; Burbine, Thomas H.;Observed spectral properties of near-Earth objects: results for population distribution, source regions, and space weathering processes; Icarus, Volume 170, Issue 2, p. 259-294.(August 2004) DOI: 10.1016/j.icarus.2004.04.004

Bus, S. J.; Vilas, F.; Barucci, M. A.; Visible-Wavelength Spectroscopy of Asteroids, in
Asteroids III, W. F. Bottke Jr., A. Cellino, P. Paolicchi, and R. P. Binzel (eds), University of Arizona Press, Tucson, p.169-182 (2002) Bibcode:

Mainzer, A., Bauer, J., Cutri, R., Grav, T., Kramer, E., Masiero, J., Sonnett, S., and Wright, E., Eds., NEOWISE Diameters and Albedos V2.0. urn:nasa:pds:neowise_diameters_albedos::2.0. NASA Planetary Data System, 2019,

Nugent, C. R.; Mainzer, A.; Masiero, J.; Grav, T.; Bauer, J.; The Yarkovsky Drift’s Influence on NEAs: Trends and Predictions with NEOWISE Measurements, The Astronomical Journal, Volume 144, Issue 3, article id. 75 (September 2012), DOI: 10.1088/0004-6256/144/3/75

JPL Small Body database:
MPC database:

Published by Charles Bell

The observer at MPC Observatory H47 near Vicksburg, Mississippi, USA

One thought on “Goldstone Delay Doppler Radar Images of (153201) 2000 WO107 Suggest a Bi-lobate Contact Binary Object

  1. Lance Benner at Goldstone posted additional Delay-Doppler images of (153201) 2000 WO107 obtained on November 30, 2020, and noted that the sequences of images suggest a rotation period of about 5 hours.


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