| E. L. Johnson|
main-belt · Phocaea
Ernest Leonard Johnson
| 21 August 1946|
21 August 1946
| Aisleen Johnson
1580 Betulia, 276 Adelheid, 132 Aethra, 847 Agnia, 47 Aglaja
1568 Aisleen, provisional designation 1946 QB, is a stony Phocaea asteroid from the inner regions of the asteroid belt, approximately 12.5 kilometers in diameter. It was discovered on 21 August 1946, by South African astronomer Ernest Johnson at Johannesburg Observatory in South Africa. It is named for the discoverer's wife, Aisleen Johnson.
1568 Aisleen Wikipedia
The S-type asteroid is a member of the Phocaea family, a group of asteroids with similar orbital characteristics. It orbits the Sun at a distance of 1.8–3.0 AU once every 3 years and 7 months (1,319 days). Its orbit has an eccentricity of 0.25 and an inclination of 25° with respect to the ecliptic. As no precoveries were taken, and no prior identifications were made, Aisleen's observation arc begins with its official discovery observation at Johannesburg.
In August 2000, a rotational light-curve of Aisleen was obtained from photometric observations made by Glen Malcolm at the Roach Motel Observatory (856) in California. The analysis gave a well-defined rotation period of 6.68 hours during which the brightness varied by 0.56 in magnitude (U=3). In April 2014, photometric observations by Brian D. Warner gave a period of 6.683 hours with an amplitude of 0.31 magnitude (U=3). A modeled light-curve from various data sources gave a concurring period of 6.67597 hours and found a pole of (109°,−68°).
According to the surveys carried out by the Japanese Akari satellite and NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Aisleen measures between 11.98 and 14.04 kilometers in diameter, and its surface has an albedo between 0.130 and 0.21. The Collaborative Asteroid Lightcurve Link assumes a standard albedo for Phocaea asteroids of 0.23 – derived from 25 Phocaea, the family's most massiv member and namesake – and calculates a diameter of 12.67 kilometers based on an absolute magnitude of 11.7.
This minor planet was named by the discoverer for his wife, Aisleen Johnson. Naming citation was published before November 1977 (M.P.C. 2116).