1223 Neckar
1223 Neckar, provisional designation, is a stony Koronian asteroid from the outer region of the asteroid belt, approximately in diameter. Discovered by Karl Reinmuth at Heidelberg Observatory in 1931, the asteroid was named for the German river Neckar. The S-type asteroid has a rotation period of 7.8 hours.
Discovery
Neckar was discovered on 6 October 1931, by German astronomer Karl Reinmuth at Heidelberg Observatory in southwest Germany. Five nights later, it was independently discovered by Fernand Rigaux at Uccle in Belgium. The Minor Planet Center only acknowledges the first discoverer. The asteroid was observed as at Heidelberg in November 1907, extending its observation arc by 24 years prior to its official discovery observation.Orbit and classification
Neckar is a core member of the Koronis family, a very large outer asteroid family with nearly co-planar ecliptical orbits. The family, named after 158 Koronis, is thought to have been formed at least two billion years ago in a catastrophic collision between two larger bodies. It orbits the Sun in the outer main-belt at a distance of 2.7–3.0 AU once every 4 years and 10 months. Its orbit has an eccentricity of 0.06 and an inclination of 3° with respect to the ecliptic.Physical characteristics
In the Tholen classification, Neckar is a common stony S-type asteroid. It has also been characterized as an S-type by Pan-STARRS.Rotation period
Best rated rotational lightcurve of Neckar gave a rotation period of 7.763 and 7.81 hours with a brightness variation of 0.18 and 0.45 magnitude, respectively. Photometric observations taken by Richard Binzel and Ed Tedesco in the 1970s and 1980s, however, gave a longer period and are now considered incorrect.Two lightcurves in the R-band with a period of 7.80 and 7.8273 hours were also obtained at the Palomar Transient Factory in 2010 and 2014, respectively. Neckars spin axes has been determined several times. The best rated result, from a group led by Polish astronomers, gave two poles at and in ecliptic coordinates.