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Over the past ten years, nearly 200 extrasolar planets have been discovered orbiting nearby solar-like stars, and the discoveries of transiting planets such as HD 209458 b, HD 149026 b, HD 189733 b, and TrES-1 have added an additional element of excitement to the quest for alien solar systems. Furthermore, the past ten years have seen the introduction of highly affordable small telescopes equipped with sensitive CCD detectors. A large number of amateur astronomers and small colleges own observatories which, when properly configured, are capable of reliably detecting the periodic dimming that occurs when a close-in giant planet passes in front of its parent star as seen from Earth. This technique has been used by amateurs worldwide to detect planetary transits.

Transitsearch.org is a cooperative observational effort designed to allow experienced amateur astronomers and small college observatories to discover transiting extrasolar planets. In order to utilize the advantages of a network of small telescopes most effectively, our strategy is to observe known planet-bearing stars at the dates and times when transits are expected to occur.

At present, the majority of confirmed extrasolar planets have been discovered using the Doppler radial velocity technique (see the tutorials at www.oklo.org). The Doppler method, however, cannot determine the inclination of a planetary orbit to the line of sight from Earth. Therefore, each planet discovered by the Doppler method has an a-priori probability of transiting, which depends mainly on the orbital period of the planet. Short-period planets have relatively high transit probabilities, whereas long-period planets have low transit probabilities.

Transitsearch.org concentrates on the known planet-bearing stars that have the highest probabilities of displaying transits. Observers from both the Northern and Southern hemispheres are encouraged to participate, and indeed, global coverage is necessary to fully check the catalog of planets. Our campaigns are usually carried out in collaboration with the American Association of Variable Star Observers, who maintain campaign websites with discussion groups, sky charts, observing tips, photometric curves, and other information. The transitsearch candidates site provides up-to-date ephemeris and transit search results for all known extrasolar planets. We also have a candidate assignment algorithm which returns a rank-ordered candidate list to observers who specify a desired observation windo w and location on Earth.

Although transiting Jupiter-sized planets can be observed using ordinary commercial-grade telescopes and CCD detectors, a great deal of dedication and patience is required. The discoveries made by the transitsearch network will be confirmed by professional observers (specifically the UC-Carnegie Planet Search Program) and the publication of the discoveries will credit the contributing members of the detection network as both discoverers and co-authors.

Members of the public who want to participate in extrasolar planet research, but who do not own telescopes, are encouraged to join the systemic collaboration, to be launched in early 2006.

Transitsearch.org gratefully acknowledges support from the NASA Origins of Solar Systems Program.

Last updated: Dec. 7, 2005, 12:18 PST