C-type asteroid. The Imhilde family's overall spectral type is CX. Rotation period In April 2003, a rotational lightcurve of Imhilde was obtained from photometric observations by Brian Warner at the Palmer Divide Observatory in Colorado. In 2011, after more than a decade of additional experience in asteroid lightcurve photometry, Warner reexamined the data set using improved tools and techniques. Lightcurve analysis gave a rotation period of hours with a brightness variation of magnitude (). Originally, the same data gave a period of hours with an amplitude magnitude (). Diameter and albedo According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer (WISE), the Infrared Astronomical Satellite IRAS, and the Japanese Akari satellite, Imhilde measures (), () and () kilometers in diameter and its surface has a low albedo of (), () and (), respectively. The Collaborative Asteroid Lightcurve Link derives an albedo of 0.0476 and a diameter of 48.39 km based on an absolute magnitude of 10.5. Further published mean-diameters and albedos by the WISE team include () and () and albedos of () and (). An asteroid occultation observed on 8 November 2011, gave a best-fit ellipse dimension of 49.0 × 49.0 kilometers. These timed observations are taken when the asteroid passes in front of a distant star. However the quality of the measurement is rated poorly. Notes References External links Lightcurve Database Query (LCDB), at www.minorplanet.info Dictionary of Minor Planet Names, Google books Discovery Circumstances: Numbered Minor Planets (1)-(5000) – Minor Planet Center 000926 Discoveries by Karl Wilhelm Reinmuth Named minor planets 19200215