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Further Analysis of Stellar Variability and CCD Precision

Further Analysis of Stellar Variability and CCD Precision

J. M. Jenkins
SETI Institute, Mountain View CA

W. J. Borucki
NASA Ames Research Center, Moffett Field CA

E. W. Dunham
Lowell Observatory, Flagstaff AZ

J. S. McDonald
SETI Institute, Mountain View CA

The Kepler mission will observe ~120,000 stars to detect 0.01% drops in brightness due to transits of Earth-sized planets, which must be recognized against intrinsic stellar variability, detector and photon noise. We examined a backside-illuminated CCD under Kepler-like conditions, and obtained a total precision of 1.3¥10-5 at a flux of 1010 e-, indicating a detector error of 7¥10-6. Using ACRIM1 solar irradiation measurements as a baseline, we conclude that intrinsic stellar variability, together with the expected photon and detector noise, provide an average SNR of 8-sigma for four transit events, yielding an 85% detection rate with less than one false alarm for the entire mission.