Measuring the changes in light from an asteroid over time (lightcurve observations) is one of the more important and productive research projects for those with modest instruments, that is, small (0.3m to 1.0m) telescopes with high-end commercial CCD cameras. While the instrumentation may be humble, the contribution to science is anything but, because from such observations it is possible to determine the rotation rate of an asteroid, its taxonomic class based on multi-color photometry, its absolute magnitude (and thus its approximate size), the surface light scattering properties, and sometimes even an initial indication of its shape and spin axis orientation. Knowledge of these characteristics is critical to new theories regarding the development and evolution of the asteroids within our Solar System and, to some degree, of systems beyond our Sun. To date, this project has generated hundreds of lightcurves and nearly a dozen shape models, and has also discovered eight new binary asteroids, six within the inner main belt where tidal encounters can not be easily used to explain binary formation. This research is critical for understanding two effects of the thermal re-radiation of sunlight by asteroids: the Yarkovsky effect changes the size of an asteroid's orbit, and the YORP effect (Yarkovsky-O'Keefe-Radzievskii-Paddack) is responsible for aligning the spin axes within asteroid families.
This program is coordinated with other programs through a regular article in the Minor Planet Bulletin, email alert services, a web site (CALL, the Collaborative Asteroid Lightcurve Link), responses to "target of opportunity" observing requests, and the asteroid Lightcurve Database (LCDB). These activities enhance both the intellectual value and the broader impact of this work. This study engages a large number of students and faculty at educational institutions around the world, as well as the general public ('backyard astronomers') in critical astronomical research. In an effort to expand the pool of qualified observers, this project includes a series of photometry workshops to provide both theory and hands-on skills to help possible future participants to contribute.
