[1] Oshima has been characterized as a carbonaceous C-type asteroid by Pan-STARRS and in the SDSS-based taxonomy.
[3][15] In September 2006, a rotational lightcurve of Oshima was obtained from photometric observations by French amateur astronomer Laurent Bernasconi.
Lightcurve analysis gave a rotation period of 12.54±0.02 hours with a brightness amplitude of 0.28 magnitude (U=2).
[9][12] 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, Oshima measures between 22.657 and 30.47 kilometers in diameter and its surface has an albedo between 0.04 and 0.086.
[5][6][7][8][10][11] The Collaborative Asteroid Lightcurve Link derives an albedo of 0.0479 and a diameter of 25.32 kilometers based on an absolute magnitude of 11.9.