773 Irmintraud, provisional designation 1913 TV, is a dark and reddish, rare-type asteroid from the outer region of the asteroid belt, about 92 kilometers in diameter. It was discovered on 22 December 1913, by German astronomer Franz Kaiser at Heidelberg Observatory in southern Germany. The asteroid is classified as a D-type and T-type body in the Tholen and SMASS taxonomy, respectively. The rare spectral T-type is similar to D-types which are often found among Jupiter trojans thought to have originated from the Kuiper belt. It orbits the Sun at a distance of 2.6–3.1 AU once every 4 years and 10 months (1,763 days). Its orbit is tilted by 17 degrees to the plane of the ecliptic and shows a low eccentricity of 0.08. According to the surveys carried out by the Infrared Astronomical Satellite, IRAS, the Japanese Akari satellite, and the Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, the minor planet's low albedo lies in the range of 0.04–0.05. It has a well-defined rotation period of 6.75 hours, determined by several concurring observations. 773 Irmintraud commemorates the antiquated German feminine name, Irmtraud, that appears frequently in old songs and sagas. The asteroid is a likely source of the Tagish Lake meteorite which landed in Canada on January 18, 2000. History In 1992, Larry Lebofsky and colleagues published an article in which they noted that "unaltered asteroids are thought to represent the raw materials available for terrestrial planet formation and so are important to our understanding of the origin and evolution of the Solar System." Since at least 1980, it was believed that D-type asteroids were unaltered asteroids, ultraprimitive in composition and composed largely of hydrated silicates and organic material. However, in analyzing the spectra of 773 Irmintraud for the water of hydration band (the 3-μm absorption feature of hydrated silicates), Lebofsky discovered the first D-type asteroid to show the water of hydration band on the surface of the asteroid. Lebofsky concluded that 773 Irmintraud had undergone an alteration process typically seen in a C-type asteroid, making 773 Irmintraud and perhaps other D-type asteroids less likely to represent the raw materials available for terrestrial planet formation. In addition, the discovery of water of hydration band on 773 Irmintraud meant that there may be major differences in mineralogy within individual type classification and astronomers must be careful in assuming that the C-, D-, and other type classification relate directly to