Dr. Warner and his team continue their existing program to produce about 100 asteroid lightcurves per year. Lightcurve observations measure the changes in light from an asteroid over time, and are among the productive research projects that can be done with modest instrument (less than 0.5-m) telescopes and high-end commercial CCD cameras. Smaller telescopes can obtain lightcurves for modeling of objects as small as about 2-5 km and up to the largest asteroids. Lightcurve observations are obtained in a few days to weeks, and from these data it is possible to determine the rotation rate of an asteroid, its taxonomic class based on multi-color photometry, absolute magnitude (and thus its approximate size), surface light scattering properties, and sometimes an initial indication of its shape and the spin axis orientation. These characteristics provide constraints on theories regarding the development and evolution of the asteroids within our Solar System. The results help to understand two processes involving the thermal re-radiation of sunlight by asteroids: First, the Yarkovsky effect, which changes the size of an object's orbit and, second, the YORP effect (Yarkovsky-O'Keefe-Radzievskii-Paddack), which is believed to be responsible for aligning the spin axes within asteroid groups or families. The YORP effect is thought to be the primary mechanism for forming small binary asteroids by causing a parent asteroid to spin up to a point where it sheds mass that becomes a satellite. . The project has also lead to the discovery of a dozen binary asteroids, and more discoveries might follow. The new lightcurve data are used to develop ideas on binary formation, spin axis orientation, and orbital migration, along with more clearly defining the role of the Yarkovsky and YORP effects on asteroid evolution. Dr. Warner and his team coordinate their efforts with other lightcurve and binary search programs through regularly published quarterly articles in the Minor Planet Bulletin that lists potential targets; the CALL (Collaborative Asteroid Lightcurve Link) web site that lists targets and provides a 'reservation' system to help coordinate observing efforts; and through maintaining the asteroid Lightcurve Database (LCDB). This database gives up-to-date results of all lightcurve results and is frequently used by other researchers. This project engages a large number of high school and undergraduate students and faculty at educational institutions around the world, as well as the general public ('backyard astronomers') in astronomical research.
