1194 Aletta, provisional designation 1931 JG, is a carbonaceous asteroid from the outer region of the asteroid belt, approximately 55 kilometers in diameter. It was discovered on 13 May 1931, by South African astronomer Cyril JacksonatJohannesburg Observatory in South Africa.[13] It was later named after the discoverer's wife Aletta Jackson.[2]
Aletta is a dark C-type asteroid and orbits the Sun at a distance of 2.6–3.2 AU once every 4 years and 12 months (1,816 days). Its orbit has an eccentricity of 0.09 and an inclination of 11° with respect to the ecliptic.[1] The body's observation arc begins at Johannesburg, one week after its official discovery observation. No precoveries were taken and no prior identifications were made.[13]
According to the surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite, and NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Aletta measures between 41.358 and 55.39 kilometers in diameter, and its surface has an albedo between 0.03 and 0.87.[4][5][6][7][8] The Collaborative Asteroid Lightcurve Link derives an albedo of 0.0333 and a diameter of 55.23 kilometers based on an absolute magnitude of 10.6.[3]
In November 2007, American astronomer James W. Brinsfield obtained the first ever lightcurveofAletta with period of 19.7 hours and a brightness variation of 0.32 magnitude at Via Capote Observatory (U=2).[9] Two more lightcurves were obtained by Australian astronomer Julian Oey at Leura/Kingsgrove Observatory in March 2010, and by the Survey conducted at the Palomar Transient Factory, California, in October 2012. Lightcurve analysis gave a concurring rotation period of 20.39 and 20.3903 hours with an amplitude of 0.28 and 0.27 magnitude, respectively (U=2+/2).[10][11]
^ 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)
