In October 2010, a rotational lightcurve of Raïssa was obtained from photometric observations at the Bigmuskie Observatory (B88), Italy, and the Etscorn Campus (719) and Organ Mesa Observatory (G50) in New Mexico, United States. Lightcurve analysis gave a rotation period of 142.79 hours with a brightness variation of 0.56 magnitude (U=3-).[11] Previous observations with a shorter period were superseded.[13][12]
With a rotation period of close to six Earth days, Raïssa is a slow rotator as most asteroids have periods of 20 hours or less. Collaborations of observers located on different longitudes, e.g. in the U.S. and Europe are especially important for asteroids with very long periods. The observers can follow the bodies brightness variation at different starting points and thereby cover parts of the lightcurve that were missed by other observers during their daytime.[11]
Poles
In 2016, a modeled lightcurve using photometric data from various sources gave a concurring period of 143.644±0.005 hours and two spin axis of (222.0°, −66°) and (40.0°, −77.0°) in ecliptic coordinates.[5][14]
Diameter and albedo
According to the surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Raïssa measures between 19.421 and 23.69 kilometers in diameter and its surface has an albedo between 0.1592 and 0.228.[6][7][8][10] The Collaborative Asteroid Lightcurve Link derives an albedo of 0.1538 and a diameter of 23.66 kilometers based on an absolute magnitude of 10.78.[9]
^ abcdUsui, 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)
^Hanus, J.; Durech, J.; Oszkiewicz, D. A.; Behrend, R.; Carry, B.; Delbo, M.; et al. (February 2016). "New and updated convex shape models of asteroids based on optical data from a large collaboration network". Astronomy and Astrophysics. 586: 24. arXiv:1510.07422. Bibcode:2016A&A...586A.108H. doi:10.1051/0004-6361/201527441.