1680 Per Brahe

1680 Per Brahe, provisional designation, is a bright background asteroid from the central region of the asteroid belt, approximately 14 km in diameter. It was discovered on 12 February 1942, by Finnish astronomer Liisi Oterma at Turku Observatory in Southwest Finland. The stony S-type asteroid has a rotation period of 3.4 hours. It is named after Swedish count and governor Per Brahe the Younger.

Orbit and classification
The S-type asteroid is a non-family asteroid of the main belt's background population. It orbits the Sun in the central main-belt at a distance of 2.2–3.2 AU once every 4 years and 6 months (1,643 days; semi-major axis of 2.73 AU). Its orbit has an eccentricity of 0.18 and an inclination of 4° with respect to the ecliptic. Per Brahe was first identified as at Heidelberg Observatory in 1902, extending the asteroid's observation arc by 40 years prior to its official discovery observation.

Naming
This minor planet was named for Swedish count Per Brahe (1602–1680), who was Governor General of Finland in the 17th century. His prosperous legacy saw the establishment of Academia Aboensis, the first university in Finland, the construction of various new towns and many schools, and the publication of the first Finnish Bible. The official was published by the Minor Planet Center on 1 April 1980 (M.P.C. 5280).

Lightcurve
In December 2012, two rotational lightcurves of Per Brahe were obtained by American astronomers Robert Stephens and Brian Warner. They gave a well-defined rotation period of 3.426 and 3.428 hours with a brightness variation of 0.13 and 0.017 magnitude, respectively (U=3/3). Previously, lightcurves obtained by Laurent Bernasconi and René Roy in 2005 and 2006, gave a similar period of 3.444 and 3.44 hours, respectively.(U=2/1+).

Diameter and albedo
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, Per Brahe measures between 13.96 and 18.29 kilometers in diameter, and its surface has an albedo between 0.178 and 0.300. The Collaborative Asteroid Lightcurve Link derives a higher albedo of 0.341 and a diameter of 14.36 kilometers with an absolute magnitude of 11.0.