Lightcurve, Color and Phase Function Photometry of the OSIRIS-REx Target Asteroid (101955) Bennu

• Published in: Icarus (New York, N.Y. 1962) Vol. 226; no. 1; pp. 663 - 670
• Main Authors: Hergenrother, Carl W., Nolan, Michael C., Binzel, Richard P., Cloutis, Edward A., Barucci, Maria Antonietta, Michel, Patrick, Scheeres, Daniel J., d’Aubigny, Christian Drouet, Lazzaro, Daniela, Pinilla-Alonso, Noemi, Campins, Humberto, Licandro, Javier, Clark, Beth E., Rizk, Bashar, Beshore, Edward C., Lauretta, Dante S.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.09.2013; Elsevier
• Subjects: Albedo; Asteroid missions; Asteroids; Asteroids, Rotation; Astrophysics; Color; NASA; Near-Earth objects; Night; Photometry; Physics; Slopes; Asteroids, Rotation; Near-Earth objects; Asteroids; Photometry
• ISSN: 0019-1035; 1090-2643
• DOI: 10.1016/j.icarus.2013.05.044

•Photometric characterization of (101955) Bennu, target of the OSIRIS-REx mission, was conducted between the years 2005–2012.•The rotation period, ECAS colors, BVRI colors and phase function were determined.•Color photometry is consistent with being a primitive B-type carbonaceous asteroid.•A linear phase slope of 0.040±0.003 magnitudes per degree of phase angle is consistent with an albedo of 0.03–0.04. 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±0.0065h, 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. [2011]. Icarus 216, 462–475). A search for the 0.7μm hydration feature using the method of Vilas (Vilas, F. [1994]. 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. [2000]. Icarus 147, 94–105).