PLANETARY CANDIDATES OBSERVED BY <i>KEPLER</i> . III. ANALYSIS OF THE FIRST 16 MONTHS OF DATA

Abstract

New transiting planet candidates are identified in sixteen months (May 2009 -\nSeptember 2010) of data from the Kepler spacecraft. Nearly five thousand\nperiodic transit-like signals are vetted against astrophysical and instrumental\nfalse positives yielding 1,091 viable new planet candidates, bringing the total\ncount up to over 2,300. Improved vetting metrics are employed, contributing to\nhigher catalog reliability. Most notable is the noise-weighted robust averaging\nof multi-quarter photo-center offsets derived from difference image analysis\nwhich identifies likely background eclipsing binaries. Twenty-two months of\nphotometry are used for the purpose of characterizing each of the new\ncandidates. Ephemerides (transit epoch, T_0, and orbital period, P) are\ntabulated as well as the products of light curve modeling: reduced radius\n(Rp/R*), reduced semi-major axis (d/R*), and impact parameter (b). The largest\nfractional increases are seen for the smallest planet candidates (197% for\ncandidates smaller than 2Re compared to 52% for candidates larger than 2Re) and\nthose at longer orbital periods (123% for candidates outside of 50-day orbits\nversus 85% for candidates inside of 50-day orbits). The gains are larger than\nexpected from increasing the observing window from thirteen months (Quarter 1--\nQuarter 5) to sixteen months (Quarter 1 -- Quarter 6). This demonstrates the\nbenefit of continued development of pipeline analysis software. The fraction of\nall host stars with multiple candidates has grown from 17% to 20%, and the\npaucity of short-period giant planets in multiple systems is still evident. The\nprogression toward smaller planets at longer orbital periods with each new\ncatalog release suggests that Earth-size planets in the Habitable Zone are\nforthcoming if, indeed, such planets are abundant.\n