American Astronomical Society, DPS meeting #46, #213.04
Hergenrother, C. W.; Hill, Dolores H.; Spitz, Anna; Barucci, Maria Antonietta; Binzel, Richard P.; Beshore, Ed; Bottke, William; Brucato, John Robert; Clark, Beth E.; Cloutis, Edward et al.
OSIRIS-REx Target Asteroids! is an award-winning citizen science project conducted as part of the Communications and Public Engagement program of the NASA OSIRIS-REx asteroid sample return mission. The project furthers the study of near-Earth asteroids (NEA) and promotes interest among the amateur astronomy community. The goal of Target Asteroids! is to expand the pool of observers who can contribute to the characterization of NEAs. We also seek to coordinate the observation of specific asteroids in order to maximize the usefulness of the data and to minimize duplication of effort.Target Asteroids! was originally focused on a list of ~80 NEAs suitable for spacecraft sample return compiled by the OSIRIS-REx science team. The list was constrained to NEAs with absolute magnitude H < 21.5, perihelion distance > 0.8 AU, aphelion distance < 2.0 AU and inclination < 8°. Since many sample return targets are beyond the reach of typical amateur telescopes (limiting magnitudes of ~14 to 20), the program was expanded to include other objects, namely asteroids that shed light on the properties of OSIRIS-REx target (101955) Bennu, bright NEAs making relatively close approaches to Earth and radar target NEAs. An introductory paper on the goals and methods of Target Asteroids! was published in the Minor Planet Bulletin (Hergenrother & Hill, Minor Planet Bulletin 40, 164-166, 2013).Since 2012, over 100 participants with a wide range of instrumentation and experience from around the world have contributed photometry of 53 asteroids. While small telescope users cannot produce high S/N observations for faint objects, they do have the advantage of being able to make observations often. A large number of low S/N observations are useful if made over different observing geometries. Utilizing many photometric observations made at different times and phase angles, small telescope users can produce direct measurements of the phase function, absolute magnitude, broadband color, and rotation period of NEAs. These parameters can be used to make determinations of taxonomy, albedo, size and other physical parameters.