3700 Geowilliams
Discovery [1]
Discovered byC. Shoemaker
E. Shoemaker
Discovery sitePalomar Obs.
Discovery date23 October 1984
Designations
(3700) Geowilliams
Named after
George E. Williams [1]
(Australian geologist)
1984 UL2 · 1973 YF2
1977 UJ
main-belt [1][2] · (inner)[3]
background [4]
Orbital characteristics [2]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc43.54 yr (15,902 d)
Aphelion2.9602 AU
Perihelion1.8695 AU
2.4148 AU
Eccentricity0.2258
3.75 yr (1,371 d)
293.18°
0° 15m 45.36s / day
Inclination12.121°
289.16°
153.06°
Physical characteristics
Mean diameter
7.712±0.130 km[5]
7.74±1.83 km[6]
7.753±0.152 km[7]
8.70±0.30 km[8]
8.82±0.86 km[9]
8.97 km (calculated)[3]
14.383±0.0183 h[10]
14.387±0.003 h[lower-alpha 1]
0.20 (assumed)[3]
0.227±0.045[9]
0.23±0.13[6]
0.233±0.033[8]
0.2970±0.0516[5]
SMASS = S k [2]
12.443±0.002 (R)[10]
12.50[5][8][9]
12.6[2][3]
12.89[6]
12.94±0.46[11]

    3700 Geowilliams, provisional designation 1984 UL2, is a stony background asteroid from the inner regions of the asteroid belt, approximately 8 kilometers (5 miles) in diameter. It was discovered on 23 October 1984, by American astronomer couple Carolyn and Eugene Shoemaker at the Palomar Observatory in California, United States.[1] The S k-subtype has a rotation period of 14.38 hours. It was named for Australian geologist George E. Williams.[1]

    Orbit and classification

    Geowilliams is a non-family asteroid from the main belt's background population.[4] It orbits the Sun in the inner main-belt at a distance of 1.9–3.0 AU once every 3 years and 9 months (1,371 days; semi-major axis of 2.41 AU). Its orbit has an eccentricity of 0.23 and an inclination of 12° with respect to the ecliptic.[2] The body's observation arc begins with its first observation as 1973 YF2 at Crimea-Nauchnij in December 1973, almost 11 years prior to its official discovery observation at Palomar.[1]

    Physical characteristics

    In the SMASS classification, Geowilliams is a Sk-subtype that transitions between the common S-type asteroid and the K-type asteroid. The latter spectral type is often found among members of the Eos family.[2]

    Rotation period

    In January 2008, a rotational lightcurve of Geowilliams was obtained from photometric observations by Australian amateur astronomer David Higgins at the Hunters Hill Observatory (E14). Lightcurve analysis gave a well-defined rotation period of 14.387 hours with a brightness variation of 0.40 magnitude (U=3).[lower-alpha 1] In July 2010, a similar period of 14.383 hours and an amplitude of 0.42 was measured at the Palomar Transient Factory in California (U=2).[10]

    Diameter and albedo

    According to the surveys carried out by the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Geowilliams measures between 7.712 and 8.82 kilometers in diameter and its surface has an albedo between 0.227 and 0.297.[5][6][7][8][9]

    The Collaborative Asteroid Lightcurve Link assumes a standard albedo for a stony asteroid of 0.20, and calculates a diameter of 8.97 kilometers based on an absolute magnitude of 12.6.[3]

    Naming

    This minor planet was named after Australian geologist George E. Williams who discovered the Acraman crater when he worked for BHP in South Australia. The old 90-kilometer impact structure is one of the largest meteorite impact craters known on Earth and the largest one on the Australian continent.[1] The official naming citation was published by the Minor Planet Center on 2 February 1988 (M.P.C. 12810).[12]

    Notes

    1. 1 2 David Higgins (2011): rotation period 14.387±0.003 hours with a brightness amplitude of 0.40±0.02 mag. Quality code is 3. Summary figures for (3700) Geowilliams at the LCDB and archived website of the Hunters Hill Observatory by David Higgins.

    References

    1. 1 2 3 4 5 6 7 "3700 Geowilliams (1984 UL2)". Minor Planet Center. Retrieved 14 May 2018.
    2. 1 2 3 4 5 6 "JPL Small-Body Database Browser: 3700 Geowilliams (1984 UL2)" (2017-07-04 last obs.). Jet Propulsion Laboratory. Retrieved 14 May 2018.
    3. 1 2 3 4 5 "LCDB Data for (3700) Geowilliams". Asteroid Lightcurve Database (LCDB). Retrieved 14 May 2018.
    4. 1 2 "Asteroid 3700 Geowilliams – Proper Elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 29 October 2019.
    5. 1 2 3 4 Mainzer, A.; Grav, T.; Masiero, J.; Hand, E.; Bauer, J.; Tholen, D.; et al. (November 2011). "NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results". The Astrophysical Journal. 741 (2): 25. arXiv:1109.6407. Bibcode:2011ApJ...741...90M. doi:10.1088/0004-637X/741/2/90. S2CID 35447010. (catalog)
    6. 1 2 3 4 Nugent, C. R.; Mainzer, A.; Bauer, J.; Cutri, R. M.; Kramer, E. A.; Grav, T.; et al. (September 2016). "NEOWISE Reactivation Mission Year Two: Asteroid Diameters and Albedos". The Astronomical Journal. 152 (3): 12. arXiv:1606.08923. Bibcode:2016AJ....152...63N. doi:10.3847/0004-6256/152/3/63.
    7. 1 2 Masiero, Joseph R.; Grav, T.; Mainzer, A. K.; Nugent, C. R.; Bauer, J. M.; Stevenson, R.; et al. (August 2014). "Main-belt Asteroids with WISE/NEOWISE: Near-infrared Albedos". The Astrophysical Journal. 791 (2): 11. arXiv:1406.6645. Bibcode:2014ApJ...791..121M. doi:10.1088/0004-637X/791/2/121. S2CID 119293330.
    8. 1 2 3 4 Masiero, Joseph R.; Mainzer, A. K.; Grav, T.; Bauer, J. M.; Cutri, R. M.; Nugent, C.; et al. (November 2012). "Preliminary Analysis of WISE/NEOWISE 3-Band Cryogenic and Post-cryogenic Observations of Main Belt Asteroids". The Astrophysical Journal Letters. 759 (1): 5. arXiv:1209.5794. Bibcode:2012ApJ...759L...8M. doi:10.1088/2041-8205/759/1/L8. S2CID 46350317.
    9. 1 2 3 4 Usui, Fumihiko; Kuroda, Daisuke; Müller, Thomas G.; Hasegawa, Sunao; Ishiguro, Masateru; Ootsubo, Takafumi; et al. (October 2011). "Asteroid Catalog Using Akari: AKARI/IRC Mid-Infrared Asteroid Survey". Publications of the Astronomical Society of Japan. 63 (5): 1117–1138. Bibcode:2011PASJ...63.1117U. doi:10.1093/pasj/63.5.1117. (online, AcuA catalog p. 153)
    10. 1 2 3 Waszczak, Adam; Chang, Chan-Kao; Ofek, Eran O.; Laher, Russ; Masci, Frank; Levitan, David; et al. (September 2015). "Asteroid Light Curves from the Palomar Transient Factory Survey: Rotation Periods and Phase Functions from Sparse Photometry". The Astronomical Journal. 150 (3): 35. arXiv:1504.04041. Bibcode:2015AJ....150...75W. doi:10.1088/0004-6256/150/3/75. S2CID 8342929.
    11. ↑ Veres, Peter; Jedicke, Robert; Fitzsimmons, Alan; Denneau, Larry; Granvik, Mikael; Bolin, Bryce; et al. (November 2015). "Absolute magnitudes and slope parameters for 250,000 asteroids observed by Pan-STARRS PS1 - Preliminary results". Icarus. 261: 34–47. arXiv:1506.00762. Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007. S2CID 53493339.
    12. ↑ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 14 May 2018.
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