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Howell-Everett UBV Photometric Survey of the Kepler Field

The Howell-Everett Kepler Field UBV Survey contains a list of 4,414,002 sources observed in a survey of the NASA Kepler Mission field using Johnson/Harris U, B, and V filters in the NOAO Mosaic1.1 Camera at the WIYN 0.9m Telescope on Kitt Peak. The survey data were taken from 206 slightly-overlapping pointings that cover 191 square degrees in each of the three passbands. The area covered includes almost the entire Kepler field plus areas between the Kepler CCDs and around the perimeter of the field. The area missed inside this surveyed region is attributable to either gaps between the Mosaic Camera CCDs or areas intentionally masked to avoid reflections and other artifacts.

The survey is estimated to be complete to magnitudes as faint as U~18.7, B~19.3, and V~19.1, but varies with location due to variable observing conditions. The mean bright limits for point sources are U=10.1, B=10.6 and V=10.5, but this also varies with location. The catalog contains sources both brighter and fainter than these ranges. A recent version of DAOPHOT is used for the photometry. The photometric scales are based upon magnitude zero point corrections for each image found by transforming the g and r magnitudes for a selected set of 5500-6000K dwarfs, as classified by the Kepler Input Catalog, to predicted Johnson B magnitudes. Zeropoints for U and V magnitudes are found based on empirical Main Sequence colors for the same stars. The zero points of some exposures are further adjusted to better match photometry on overlapping, neighboring images. Magnitude uncertainties are estimated based on the combination of errors reported by DAOPHOT and an estimate of the systematic internal uncertainties seen in stars observed on multiple exposures. In the case of stars observed in multiple pointings, an average magnitude is reported along with a reduced error.

The NOAO Mosaic camera pipeline was used to perform a plate solution for each image. The position for each source is based on one image. Whenever possible, a V image is used to define the position. In the absence of a V detection, a B detection is used or, if that is lacking, the U detection.

Everett, Howell, Kinemuchi, 2012, PASP (ahead of print link) or the ADS Link.

Data available at:
or via anonymous ftp at cd /pub/hlsp/kplrubv