[2][9] Karel is a member of the Flora family, one of the largest collisional populations of stony asteroids in the inner main-belt.

[9] Astronomers François Colas, Jean Lecacheux, Federico Manzini and Raoul Behrend obtained a rotational lightcurve of Karel from photometric observations in January 2008.

[7] According to the survey carried out by the Japanese Akari satellite and NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Karel measures 4.80 and 7.27 kilometers in diameter, and its surface has an albedo of 0.278 and 0.531, respectively.

[4][5] The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.24 – derived from 8 Flora, the largest member and namesake of this family – and calculates a diameter of 7.47 kilometers based on an absolute magnitude of 12.8.

Reinmuth also named his two discoveries, 1673 van Houten and 1674 Groeneveld, after the prolific couple of Dutch astronomers.