2004JAVSO..33....1C

A typical short-period giant planet occulting a parent star can produce a ∼1% dimming of the star's light for an interval of several hours. The combination of photometric and Doppler radial velocity (RV) measurements of a transiting extrasolar planet can yield unambiguous measurements of the planet's mass, radius, density, and exact orbital parameters. In this article, we describe a low-cost observational and data- reduction pipeline which can be used to obtain 3 millimagnitude photometry with a small-aperture telescope and a consumer-grade CCD detector. This precision is sufficient to reliably detect the transit of a giant planet. We discuss noise sources, and evaluate strategies for achieving a low overall noise floor. We describe the performance of our pipeline in a successful observation of an HD 209458 "b" transit, and in a photometric survey of GJ 876 during an epoch in which we predicted that GJ 876 "c" (P ∼30d) could potentially be observed to transit. We also briefly describe the status of the ongoing www.transitsearch.org project, which coordinates a photometric search for planetary transits among known planet-bearing stars.