1541 Estonia

1541 Estonia, provisional designation, is an asteroid from the central regions of the asteroid belt, approximately 21 kilometers in diameter. It was discovered on 12 February 1939, by astronomer Yrjö Väisälä at the Iso-Heikkilä Observatory near Turku, Finland. The asteroid was named after the Baltic country of Estonia.

Orbit and classification
Estonia is a non-family asteroid from the main belt's background population. It orbits the Sun in the central main belt at a distance of 2.6–3.0 AU once every 4 years and 7 months (1,683 days). Its orbit has an eccentricity of 0.07 and an inclination of 5° with respect to the ecliptic.

The asteroid was first identified as at the Simeiz Observatory in April 1916. The body's observation arc begins with its identification as at Yerkes Observatory in November 1923, more than 15 years prior to its official discovery observation at Turku.

Physical characteristics
In the SMASS classification, Estonia is a Xc-subtype that transitions from the X-type to the carbonaceous C-type asteroids.

Rotation period
In November 2015, a rotational lightcurve of Estonia was obtained from photometric observations by French amateur astronomer René Roy. Lightcurve analysis gave a rotation period of 10.1 hours with a brightness amplitude of 0.13 magnitude (U=2-).

Diameter and albedo
According to the surveys carried out by the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Estonia measures between 19.53 and 24.542 kilometers in diameter and its surface has an albedo between 0.0976 and 0.140.

The Collaborative Asteroid Lightcurve Link derives an albedo of 0.1314 and a diameter of 20.15 kilometers based on an absolute magnitude of 11.3.

Naming
This minor planet was named after the Baltic country of Estonia, just south of the Gulf of Finland and Finland itself. The two countries are inhabited by related Balto-Finnic peoples. Estonia regained independence from Soviet rule in 1991. The official was published by the Minor Planet Center in January 1956 (M.P.C. 1350).