9298 Geake, provisional designation 1985 JM, is a Mitidika asteroid from the central regions of the asteroid belt, approximately 12 kilometers in diameter. It was discovered on 15 May 1985, by American astronomer Edward Bowell at Lowell Observatory's Anderson Mesa Station near Flagstaff, Arizona, United States.[13] The asteroid was named for British astronomer John E. Geake.[2]
The asteroid orbits the Sun in the central main-belt at a distance of 1.8–3.3 AU once every 4 years and 2 months (1,507 days). Its orbit has an eccentricity of 0.30 and an inclination of 12° with respect to the ecliptic.[1] It was first observed on a precovery taken at Palomar Observatory in May 1956, extending the body's observation arc by 29 years prior to its official discovery observation at Anderson Mesa.[13]
Physical characteristics
Lightcurves
In August 2006, a rotational lightcurve of Geake was obtained from photometric observations by American astronomer Brian Warner at his Palmer Divide Observatory (716) in Colorado. Lightcurve analysis gave a rotation period of 38.29 hours with a brightness variation of 0.78 magnitude (U=2).[11][a] While not being a slow rotator, it has a longer than average rotation, which lies normally between 2 and 20 hours. The body's high brightness amplitude of 0.78 magnitude also indicates that it has a non-spheroidal shape.
Diameter and albedo
According to the surveys carried out by the Japanese Akari satellite and NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Geake measures between 11.54 and 14.040 kilometers in diameter and its surface has a low albedo between 0.033 and 0.05.[5][6][7][8][9][10]
Contrary to the results obtained by the space-based observatories, the Collaborative Asteroid Lightcurve Link assumes a standard albedo for stony asteroids of 0.20, derived from the family's namesake,[b] and consequently calculates a much shorter diameter of 6.50 kilometers based on an absolute magnitude of 13.3, as the higher a body's reflectivity the smaller its diameter for a given brightness.[3]
^ abLightcurve plot of 9298 Geake with a rotation period 38.29±0.02 hours with a brightness amplitude of 0.78±0.03 by B. D. Warner at the Palmer Divide Observatory (2006). Summary figures at LCDB
^ abcdUsui, 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)
