Expected effects of hot CCD pixels on detection of transits of
extra-solar planets with the Kepler Mission
Thomas N. Gautier*a and Ronald Gillilandb
aJet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive,
Pasadena, California 91109
bSpace Telescope Science Institute, 3700 San Martin Dr., Baltimore, MD 21218
ABSTRACT
Detection of Earth sized extra-solar planets by the transit method requires measurement of quite small variations
(~8x10-5) in the brightness of candidate stars. Noise contributed by hot pixels in CCD detectors operating in the space
environment, among other noise sources, must be understood and controlled in order to design transit experiments like
the Kepler Mission, which will attempt to measure the distribution of planets as small as the Earth around solar type
stars from space. We have analyzed the hot pixel statistics for CCD detectors on several operating space instruments
and conclude that neither the amplitude nor the variability of hot pixels will significantly impair the ability of the Kepler
Mission to detect transits of earth sized planets transiting solar type stars. The Kepler Mission is currently in the design
stage and is expected to begin operation in 2007.
Keywords: extra-solar planets, planet detection, photometry, CCDs, space observatories, transit method, Kepler
Mission, hot pixels
1. INTRODUCTION
The Kepler Mission is a NASA Discovery mission that will search for extra-solar planets with the technique of
transit detection. Kepler is currently under development by NASA Ames Research Center, the Jet Propulsion
Laboratory, the Space Telescope Science Institute, Ball Aerospace and Technologies Corporation and Honeywell and
expects to launch in 2007. The transit technique for planet detection finds planets by recognizing the slight dimming of
the planet’s parent star as the planet passes in front of the star as seen from Earth. Kepler is being designed to find Earth
sized planets around solar like stars so it must achieve extraordinarily high sensitivity