variation of magnitude (). However, the result is ambiguous and allows for an alternative period solution of 11.92 hours. In April 2008, French amateur astronomer René Roy determined a period of hours with a low amplitude of magnitude (). In May 1984, the object's first measurement by Richard Binzel gave a period of and an amplitude of 0.23 magnitude (). Diameter and albedo According to the surveys carried out by the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer (WISE), Hildburg measures () and () kilometers in diameter and its surface has an albedo of () and (), respectively. The Collaborative Asteroid Lightcurve Link assumes a standard albedo for a stony asteroid of 0.20 and derives a diameter of 19.28 kilometers based on an absolute magnitude of 10.94. The WISE team also published an alternative mean-diameter () and an albedo of (). On 23 August 2004, an asteroid occultation gave a best-fit ellipse dimension of () with a low quality rating of 1. These timed observations are taken when the asteroid passes in front of a distant star. References External links Lightcurve Database Query (LCDB), at www.minorplanet.info Dictionary of Minor Planet Names, Google books Asteroids and comets rotation curves, CdR – Geneva Observatory, Raoul Behrend Discovery Circumstances: Numbered Minor Planets (1)-(5000) – Minor Planet Center 000684 Discoveries by August Kopff Named minor planets 19090808