A
two chord stellar occultation by the asteroid observed in 2004 gave an approximate diameter of 50 km. French amateur astronomer
Pierre Antonini obtained a
lightcurve of
Dufour from
photometric observations taken during April 2010. Lightcurve analysis gave a well-defined
rotation period of hours with an amplitude of 0.31 in
magnitude (). In August 2013, photometric observations at the
Palomar Transient Factory, California, gave a similar period of hours with a brightness variation of 0.35 (). According to the surveys carried out by the Infrared Astronomical Satellite
IRAS and the Japanese
Akari satellite,
Dufour measures 50.3 and 51.2 kilometers in diameter and its surface has an
albedo of 0.040 and 0.039, respectively. The
Collaborative Asteroid Lightcurve Link derives an albedo of 0.034 and a diameter of 50.3 kilometers with an
absolute magnitude of 10.8. == References ==