3700 Geowilliams
Main-belt asteroid
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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]
(Australian geologist)
| Discovery[1] | |
|---|---|
| Discovered by | C. Shoemaker E. Shoemaker |
| Discovery site | Palomar Obs. |
| Discovery date | 23 October 1984 |
| Designations | |
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 arc | 43.54 yr (15,902 d) |
| Aphelion | 2.9602 AU |
| Perihelion | 1.8695 AU |
| 2.4148 AU | |
| Eccentricity | 0.2258 |
| 3.75 yr (1,371 d) | |
| 293.18° | |
| 0° 15m 45.36s / day | |
| Inclination | 12.121° |
| 289.16° | |
| 153.06° | |
| Physical characteristics | |
| 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[a] | |
| 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).[a] 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
- 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.
