1523 Pieksämäki (provisional designation 1939 BC) is a stony Florian asteroid from the inner regions of the asteroid belt, approximately 9 kilometers in diameter. It was discovered on 18 January 1939 by Finnish astronomer Yrjö Väisälä at the Turku Observatory in Southwest Finland, and named for the town of Pieksämäki in eastern Finland.
Orbit and classification
This S-type asteroid is a member of the Flora family, one of the largest groups of stony asteroids in the main-belt. It orbits the Sun at a distance of 2.0–2.5 AU once every 3 years and 4 months (1,226 days). Its orbit has an eccentricity of 0.09 and an inclination of 5° with respect to the ecliptic. In 1936, it was first identified as 1936 FO1 at Nice Observatory, extending its observation arc by 3 years prior to its official discovery observation at Turku.
Physical characteristics
Lightcurves
In December 2005, a rotational lightcurve was obtained, giving a well-defined rotation period of 5.3202 hours with a brightness variation of 0.47 magnitude. Previous photometric observations in July 2004 gave an identical period with an amplitude of 0.40 magnitude. In March 2013, another well-defined period of 5.3210 hours was obtained.
Diameter and albedo
According to surveys carried out by NASA's Wide-field Infrared Survey Explorer (WISE) with its subsequent NEOWISE mission, 1523 Pieksämäki measures between 9.111 and 10.008 kilometers in diameter, and its surface has an albedo between 0.213 and 0.505.
Naming
This minor planet was named for Pieksämäki, an eastern Finnish town in Southern Savonia. The official naming citation was published by the Minor Planet Center on 20 February 1976 (M.P.C. 3929).
