In October 2006, a rotational lightcurve of Burnhamia was obtained from photometric observations by Robert Buchheim at the Altimira Observatory (G76) in California. Lightcurve analysis gave a well-defined rotation period of 13.875±0.001 hours with a brightness variation of 0.20±0.02magnitude (U=3).[10] The result supersedes previous observations by French amateur astronomer Laurent Bernasconi from May 2005, with a period of 13.9±0.03 hours with an amplitude of 0.15±0.01 magnitude (U=2+), and from October 2006, that gave a period of 13.85±0.03 hours and an amplitude of 0.22±0.02 magnitude (U=3−).[13]
Diameter and albedo
According to the surveys carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer (WISE), the Japanese Akari satellite, and the Infrared Astronomical Satellite IRAS, Burnhamia measures (61.278±0.303), (61.44±2.13) and (66.65±2.4) kilometers in diameter and its surface has an albedo of (0.071±0.008), (0.082±0.007) and (0.0698±0.005), respectively.[6][7][9][8] The Collaborative Asteroid Lightcurve Link derives an albedo of 0.0602 and a diameter of 66.64 kilometers based on an absolute magnitude of 9.55.[14] The WISE team also published an alternative mean-diameter of (66.151±1.727 km) with corresponding albedos of (0.0611±0.0082).[5][14] Two asteroid occultations of Burnhamia September 2013 and January 2014, gave both a best-fit ellipse dimension of (61.0 km × 61.0 km).[5] These timed observations are taken when the asteroid passes in front of a distant star.
^ abcMasiero, Joseph R.; Grav, T.; Mainzer, A. K.; Nugent, C. R.; Bauer, J. M.; Stevenson, R.; et al. (August 2014). "Main-belt Asteroids with WISE/NEOWISE: Near-infrared Albedos". The Astrophysical Journal. 791 (2): 11. arXiv:1406.6645. Bibcode:2014ApJ...791..121M. doi:10.1088/0004-637X/791/2/121.
^ abcUsui, Fumihiko; Kuroda, Daisuke; Müller, Thomas G.; Hasegawa, Sunao; Ishiguro, Masateru; Ootsubo, Takafumi; et al. (October 2011). "Asteroid Catalog Using Akari: AKARI/IRC Mid-Infrared Asteroid Survey". Publications of the Astronomical Society of Japan. 63 (5): 1117–1138. Bibcode:2011PASJ...63.1117U. doi:10.1093/pasj/63.5.1117. (online, AcuA catalog p. 153)