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J.M. Jenkins (SETI Institute), D.A. Caldwell (NRC/NASA A.R.C.)
With the astonishing discovery of about a dozen super giant short-period (<7 days) planets in the last five years, astronomers are turning to transit photometry to discover new planets and to confirm radial velocity detections. Indeed, ground-based transit photometry provided the first direct confirmation of a planetary detection, HD209458b. Transits of HD209458b were also detected in the Hipparcos photometry archive collected several years earlier. Several space-borne photometers have been proposed to detect extrasolar planets. The focus of NASA Ames' \emph{Kepler Mission} is the detection of Earth-size planets. In this paper we focus attention on the problem of assessing the significance of a candidate transit signature. There are two fundamental quantities of interest required to establish the confidence in a planetary candidate. These are: 1) the equivalent number of independent statistical tests conducted in searching the light curve of one star for transiting planets over a given range of periods, and 2) the characteristics of the observation noise for the light curve in question. The latter quantity determines the false alarm rate for a single test for that particular star as a function of the detection threshold. The former quantity, together with the total number of target stars in the observing program, dictate the requisite single-test false alarm rate based on the acceptable total number of false alarms. The methods described do not make any presumptions about the distribution of the observational noise. In addition they either provide conservative results for non-white noise or take the correlation structure of the noise into account. The results of this paper show that transit photometry is a promising method for detecting planets even in the presence of colored, non-Gaussian noise and with the required large number of target stars (>100,000 stars in the case of the \emph{Kepler Mission}) for the small geometric probability of transit alignment.
Support for this work was received from NASA's Discovery Program.
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The author(s) of this abstract have provided an email address for comments about the abstract: jjenkins@mail.arc.nasa.gov