A small CCD photometer dedicated to the detection of extrasolar planets has been developed and put into operation at Mount Hamilton, California. It simultaneously monitors 6000 stars brighter than 13th magnitude in its 49 deg2 field of view. Observations are conducted all night every clear night of the year. A single field is monitored at a cadence of eight images per hour for a period of about 3 months. When the data are folded for the purpose of discovering low-amplitude transits, transit amplitudes of 1% are readily detected. This precision is sufficient to find Jovian-size planets orbiting solar-like stars, which have signal amplitudes from 1% to 2% depending on the inflation of the planet’s atmosphere and the size of the star. An investigation of possible noise sources indicates that neither star field crowding, scintillation noise, nor photon shot noise are the major noise sources for stars brighter than visual magnitude 11.6. Over one hundred variable stars have been found in each star field. About 50 of these stars are eclipsing binary stars, several with transit amplitudes of only a few percent. Three stars that showed only primary transits were examined with high-precision spectroscopy. Two were found to be nearly identical stars in binary pairs orbiting at double the photometric period. Spectroscopic observations showed the third star to be a high mass ratio single-lined binary. On 1999 November 22 the transit of a planet orbiting HD 209458 was observed and the predicted amplitude and immersion times were confirmed. These observations show that the photometer and the data reduction and analysis algorithms have the necessary precision to find companions with the expected area ratio for Jovian-size planets orbiting solar-like stars.

Publication Date



© 2001. The Astronomical Society of the Pacific. All rights reserved.

This is the pre-print published by the Astronomical Society of the Pacific. The final, published version is located here: https://doi.org/10.1086/319537

The authors would like to thank the observers who spent many sleepless nights obtaining the data; especially Tim Castellano, Tony Dobrovolskis, Wendy Hansen, Carol Harper, Lynn Harper, Ralph Libby, Alan Meyer, Patrick Maloney, William Trublood. The superb work of the machine shop headed by Dave Scimeca was critical to the success of the project. Scripts to control and automate the operation of the camera were written by Bob Slawson of the Rochester Institute of Technology. John Caldwell, on sabbatical from York University, investigated the influence of star crowding on photometric precision. Robert Yee directed system operation and maintenance. Kim Kubota (Orbital Science Corp.) and Walt Miller (Man Tech Corp) directed the observers. The cooperation and help of the Lick Observatory staff, especially Remington Stone, and their permission to use the Crocker Dome made the project possible. Special thanks are due to Geoff Marcy, Paul Butler, Jack Lissauer, Eduardo Martin, David Ardilla, and Dave Latham who made spectroscopic observations of candidate stars. Advice from Tim Brown (HAO, UCAR), Ted Dunham (Lowell Obs.), and Laurence Doyle (SETI Institute) contributed the success of the project. The patience, support, and funding received from Origins and Advanced Project Offices at NASA Headquarters and the Astrobiology Office at NASA Ames is gratefully acknowledged.

Note: imported from RIT’s Digital Media Library running on DSpace to RIT Scholar Works in February 2014.

Document Type


Department, Program, or Center

Chester F. Carlson Center for Imaging Science (COS)


RIT – Main Campus