3700 Geowilliams

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]

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]

    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. 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. "3700 Geowilliams (1984 UL2)". Minor Planet Center. Retrieved 14 May 2018.
    2. "JPL Small-Body Database Browser: 3700 Geowilliams (1984 UL2)" (2017-07-04 last obs.). Jet Propulsion Laboratory. Retrieved 14 May 2018.
    3. "LCDB Data for (3700) Geowilliams". Asteroid Lightcurve Database (LCDB). Retrieved 14 May 2018.
    4. "Asteroid 3700 Geowilliams – Proper Elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 29 October 2019.
    5. 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. 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. 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. 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. 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. 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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