1803 Zwicky


1803 Zwicky, provisional designation, is a stony Phocaea asteroid from the inner regions of the asteroid belt, approximately 10 kilometers in diameter. It was discovered on 6 February 1967, by Swiss astronomer Paul Wild at Zimmerwald Observatory near Bern, Switzerland. It was later named after Swiss astronomer Fritz Zwicky.

Classification and orbit

Zwicky is a member of the Phocaea family, an asteroid family with two thousand members, named after their largest member, 25 Phocaea. It orbits the Sun in the inner main-belt at a distance of 1.8–2.9 AU once every 3 years and 7 months. Its orbit has an eccentricity of 0.25 and an inclination of 22° with respect to the ecliptic. It was first identified as at Lowell Observatory in 1931, extending the body's observation arc by 36 years prior to its official discovery observation.

Physical characteristics

Zwicky is an assumed stony S-type asteroid, in line with the overall spectral type for Phocaea family.

Lightcurves

In March 2003, a fragmentary lightcurve of Zwicky was obtained from photometric observations by French amateur astronomer Laurent Bernasconi. It gave a rotation period of 27.1 hours with a brightness amplitude of 0.08 magnitude. As of 2017, no other rotational lightcurves have been obtained.

Diameter and albedo

According to the surveys carried out by the Japanese Akari satellite and NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Zwicky measures between 9.2 and 10.2 kilometers in diameter, and its surface has an albedo between 0.25 and 0.34. The Collaborative Asteroid Lightcurve Link assumes a standard albedo for Phocaea asteroids of 0.23, and calculates a diameter of 10.54 kilometers based on an absolute magnitude of 12.2.

Naming

This minor planet was named after Swiss astronomer Fritz Zwicky, who was a professor at Caltech and a pioneer in many fields, most notably in the study of galaxy clusters and supernovas, in high-energy astrophysics, and in developing jet propulsion for spacecraft and airplanes. He was the first to infer the existence of unseen matter and coined the term Dark matter. The lunar crater Zwicky is also named in his honour. The official was published by the Minor Planet Center on 18 April 1977.