Discovered by P. Wild MPC designation 1845 Helewalda Discovered 30 October 1972 Orbits Sun | Discovery date 30 October 1972 Minor planet category main-belt · (outer) Absolute magnitude 11.3 Asteroid group Asteroid belt | |
Named after Helen Gachnang(friend of discoverer) Alternative names 1972 UC · 1931 VC11954 GG · 1971 OR1971 QX2 Similar Sun, 3552 Don Quixote, 81P/Wild | ||
1845 Helewalda, provisional designation 1972 UC, is a carbonaceous asteroid in the outer regions of the asteroid belt, approximately 20 kilometers in diameter. It was discovered by Swiss astronomer Paul Wild at Zimmerwald Observatory near Bern, Switzerland, on 30 October 1972.
The C-typeasteroid orbits the Sun at a distance of 2.8–3.1 AU once every 5 years and 1 month (1,868 days). Its orbit has an eccentricity of 0.06 and an inclination of 11° with respect to the ecliptic. The first precovery was taken at Lowell Observatory in 1931, extending the asteroid's observation arc by 41 years prior to its discovery.
Based on observations made by French astronomer René Roy in March 2010, Helewalda has a well-determined rotation period of 7000727860000000000♠7.2786±0.0002 hours with a brightness variation of 0.26 in magnitude (U=3-). Between 2009 and 2015, other light-curves were obtained at the Oakley Southern Sky Observatory in Australia (E09), the Via Capote Observatory at Thousand Oaks, California (G69), and the Palomar Transient Factory at Palomar Observatory. They gave a similar period of 7000739900000000000♠7.399±0.004, 7000740000000000000♠7.4±0.1 and 7000739850000000000♠7.3985±0.0098 hours with a corresponding amplitude of 0.20, 0.28 and 0.15, respectively (U=2/2+/2).
The Collaborative Asteroid Lightcurve Link calculates a diameter of 32.0 kilometers, based on an assumed standard albedo for carbonaceous C-type asteroids of 0.057, while the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer measured a higher albedo of 0.134 and 0.129 and a corresponding diameter of 19.9 and 20.4 kilometers in diameter, respectively.
The discoverer, Paul Wildt, named a pair of asteroids after two of his former schoolmates, Susi and Helen, both from the small village of Wald, Zürich in Switzerland. This one was dedicated to Helen Gachnang, while the previously numbered asteroid 1844 Susilva was given to Susi Petit-Pierre. Naming citation was published before November 1977 (M.P.C. 4156).