Kepler Instrument Performance: the 1 Year Checkup

The Kepler Mission is designed to detect the 80 parts per million (ppm) signal from an Earth-Sun equivalent transit. Such precision requires superb instrument stability on time scales up to 2 days and systematic error removal to better than 20 ppm. The sole scientific instrument is the photometer, a 0.95 m aperture Schmidt telescope that feeds the 94.6 million pixel CCD detector array, which contains both Science and Fine Guidance Sensor (FGS) CCDs. We find that the in-flight detector properties of the focal plane, including bias levels, read noise, gain, linearity, saturation, FGS to Science crosstalk, and video crosstalk between Science CCDs, are essentially unchanged from their pre-launch values. Now that Kepler has been collecting science data for more than a year, we are able to track stars through a complete orbit of the spacecraft around the Sun and its associated roll orientations. Using these data, we can begin to disentangle the instrument related signals from those intrinsic to the sky background and stars, measure both short- and long-term effects from cosmic rays, see interactions of previously known image artifacts with starlight, and uncover several unexpected systematics that affect photometric precision, including unexplained diffuse illumination events that occur at significant levels 10 times per month.

Funding for this Discovery Mission is provided by NASA's Science Mission Directorate.