The NASA OSIRIS-REx mission will retrieve a sample of the carbonaceous
near-Earth Asteroid (101955) Bennu and return it to Earth in 2023.
Photometry in the Eight Color Asteroid Survey (ECAS) filter system and
Johnson–Cousins V and R filters were conducted during the two most
recent apparitions in 2005/2006 and 2011/2012. Lightcurve observations
over the nights of September 14–17, 2005 yielded a synodic
rotation period of 4.2905 ± 0.0065 h, which is consistent with
the results of Nolan et al. (2013). ECAS color measurements made during
the same nights confirm the B-type classification of Clark et al.
(Clark, B.E., Binzel, R.P., Howell, E.S., Cloutis, E.A., Ockert-Bell,
M., Christensen, P., Barucci, M.A., DeMeo, F., Lauretta, D.S., Connolly,
H., Soderberg, A., Hergenrother, C., Lim, L., Emery, J., Mueller, M.
. Icarus 216, 462–475). A search for the 0.7 μm hydration
feature using the method of Vilas (Vilas, F. . Icarus 111,
456–467) did not reveal its presence. Photometry was obtained over
a range of phase angles from 15° to 96° between 2005 and 2012.
The resulting phase function slope of 0.040 magnitudes per degree is
consistent with the phase slopes of other low albedo near-Earth
asteroids (Belskaya, I.N., Shevchenko, V.G. . Icarus 147,