Discovered by K. Reinmuth MPC designation 1720 Niels Discovered 7 February 1935 Orbits Sun Asteroid group Asteroid belt | Discovery date 7 February 1935 Minor planet category main-belt · (inner) Absolute magnitude 13.2 Discoverer Karl Wilhelm Reinmuth | |
Named after Niels (discoverer's grandson) Alternative names 1935 CQ · 1940 WH1951 AL · 1953 VO11959 RA · 1963 WE Discovery site Landessternwarte Heidelberg-Königstuhl Similar 1862 Apollo, Sun, 1419 Danzig, 1056 Azalea, 1111 Reinmuthia | ||
1720 Niels, provisional designation 1935 CQ, is a stony asteroid from the inner regions of the asteroid belt, approximately 6.4 kilometers in diameter. It was discovered on 7 February 1935, by German astronomer Karl Reinmuth at Heidelberg Observatory in southern Germany.
Niels orbits the Sun at a distance of 2.0–2.4 AU once every 3 years and 3 months (1,182 days). Its orbit has an eccentricity of 0.10 and an inclination of 1° with respect to the ecliptic. First observed at Heidelberg in 1927 , Niels' observation arc begins with its official discovery observation in 1935.
A rotational light-curve of Niels was obtained by astronomer Maurice Clark in December 2005. It gave it a rotation period of 9.976 hours with a brightness variation of 0.15 magnitude (U=1). In November 2008, photometric observations by amateur astronomer Pierre Antonini gave another period of 19.2 hours with an amplitude of 0.01 (U=1-). As of 2017, a secure period for Niels has not yet been obtained.
According to the survey carried out by NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Niels measures 6.394 kilometers in diameter, and its surface has an albedo of 0.227, superseding a preliminary result that gave a slightly larger diameter and lower albedo. The Collaborative Asteroid Lightcurve Link assumes a standard albedo for stony asteroids of 0.20 and calculates a diameter of 8.18 kilometers based on an absolute magnitude of 12.8. Pan-STARRS classifies this stony asteroid as a LS-type, an intermediate to the rare L-type asteroids.
The minor planet was named by the discoverer after his grandson, Jens. Reinmuth also named 1719 Jens after one of his grandsons. Naming citation was published before November 1977 (M.P.C. 3933).