1669 Dagmar

1669 Dagmar, provisional designation, is a rare-type Themistian asteroid from the outer region of the asteroid belt, approximately 42 kilometers in diameter. It was discovered on 7 September 1934, by German astronomer Karl Reinmuth at Heidelberg Observatory in southern Germany, and named after a common German feminine name.

Classification and orbit
The asteroid is a member of the Themis family, a large group of asteroids in the outer main-belt. It orbits the Sun at a distance of 2.8–3.5 AU once every 5 years and 7 months (2,032 days). Its orbit has an eccentricity of 0.11 and an inclination of 1° with respect to the ecliptic. As no precoveries were taken, and no prior identifications were made, Dagmar's observation arc begins with its official discovery observation.

Physical characteristics
Dagmar has a rare spectra of a G-type asteroid (or Cg-type in the SMASS taxonomy), similar to 1 Ceres, the largest asteroid and only dwarf planet in the asteroid belt.

Rotation period
Astronomer Federico Manzini obtained a provisional lightcurve of Dagmar from photometric observations in March 2004. It gave a tentative rotation period of 12 hours with a brightness variation of 0.15 magnitude (U=1). As of 2017, no secure period has yet been published.

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, Dagmar measures between 35.78 and 45.194 kilometers in diameter, and its surface has an albedo between 0.035 and 0.057. The Collaborative Asteroid Lightcurve Link adopts the results obtained by 17 observations made by IRAS, that is an albedo of 0.0565 and a diameter of 35.78 kilometers with an absolute magnitude of 10.97.

Naming
This minor planet was named by the discoverer after a common German feminine name. No special meaning is assigned to this name. The official was published by the Minor Planet Center on 15 December 1968 (M.P.C. 2901).