803 Picka (prov. designation: or ) is a large and dark background asteroid from the outer regions of the asteroid belt. It was discovered on 21 March 1915, by Austrian astronomer Johann Palisa at the Vienna Observatory. The carbonaceous D-type asteroid has a rotation period of 5.1 hours and measures approximately in diameter. It was named after Czech physician Friedrich Pick (1867–1921). Orbit and classification Picka is a non-family asteroid of the main belt's background population when applying the hierarchical clustering method to its proper orbital elements. It orbits the Sun in the outer asteroid belt at a distance of 3.0–3.4 AU once every 5 years and 9 months (2,094 days; semi-major axis of 3.2 AU). Its orbit has an eccentricity of 0.07 and an inclination of 9° with respect to the ecliptic. On 8 July 1899, the asteroid was first observed as at the Boyden Station of the Harvard Observatory in Arequipa, Peru. The body's observation arc begins with its official discovery observation by Johann Palisa at Vienna Observatory on 21 March 1915. Naming This minor planet was named after Czech physician Friedrich Pick (1867–1921) from Prague , who was the first physician to introduce endoscopic methods in medicine. According to the 1917 edition of the astronomical calendar in German "Astronomischer Kalender für 1917", the asteroid was named by friends of the discoverer Johann Palisa. The was mentioned in The Names of the Minor Planets by Paul Herget in 1955 (). Physical characteristics In the SDSS-based taxonomy, Picka is a dark D-type asteroid. In the 1995 SMASS-I survey by Xu, it is classified as an uncommon T-type with some similarities to a D-type (TD). The D-types asteroids are common in the outer main-belt and are very abundant among the Jupiter trojan population. Rotation period In April 2007, a rotational lightcurve of Picka was obtained from photometric observations by French amateur astronomer Pierre Antonini. Lightcurve analysis gave a well-defined rotation period of hours with a high brightness variation of magnitude, indicative of an elongated shape (). Alternative and lower-rated photometric observations were made by Jean-Gabriel Bosch in February 2006, and again by Pierre Antonini in November 2010, which gave a period of and hours with an amplitude of and magnitude (). Lightcurve inversion also modeled the body's shape and poles. In 2013, modelling by an international study using photometric data from the US Naval Observatory, the Uppsala Asteroid Photometric Catalogue,