New Binary and Exoplanet Candidates from STEREO Light Curves

The Heliospheric Imagers (HI) onboard the STEREO satellites are observing an abundance of background stars as they follow their respective Sun-centered orbits. These are wide-angled CCD cameras with a 20°×20° field of view, directed ~14° from the solar disk. These imagers monitor 20% of the sky over one year, providing light curves for over 500,000 stars down to 12th magnitude and brighter than 7th. We are currently analysing the photometric data from the HI-1 cameras, obtained since March 2007. Following a standard data reduction of the raw photometric images, the resultant light curves underwent a sequence of detrending procedures to minimize systematics in the data, which can contribute to red noise. A transit search was performed using the BLS algorithm, which is sensitive to the box-like shape associated with planetary transits. The resulting candidates were subjected to a number of false-alarm tests to determine the most promising candidates and these were investigated further, visually and using available catalogue data. Possible new exoplanet and binary candidates will now be submitted for follow-up photometric and spectroscopic observations to confirm their nature.