Article

A two-color CCD survey of the North Celestial Cap: I. The method

Astrophysics and Space Science (Impact Factor: 2.4). 12/2009; 326(2). DOI: 10.1007/s10509-009-0242-0
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ABSTRACT We describe technical aspects of an astrometric and photometric survey of the North Celestial Cap (NCC), from the Pole ( δ=90°) to δ=80°, in support of the TAUVEX mission. This region, at galactic latitudes from ˜17° to ˜37°, has poor coverage in modern CCD-based surveys. The observations are performed with the Wise Observatory one-meter reflector and with a new mosaic CCD camera (LAIWO) that images in the Johnson-Cousins R and I bands a one-square-degree field with sub-arcsec pixels. The images are treated using IRAF and SExtractor to produce a final catalogue of sources. The astrometry, based on the USNO-A2.0 catalogue, is good to ˜1 arcsec and the photometry is good to ˜0.1 mag for point sources brighter than R=20.0 or I=19.1 mag. The limiting magnitudes of the survey, defined at photometric errors smaller than 0.15 mag, are 20.6 mag ( R) and 19.6 ( I). We separate stars from non-stellar objects based on the object shapes in the R and I bands, attempting to reproduce the SDSS star/galaxy dichotomy. The completeness test indicates that the catalogue is complete to the limiting magnitudes.

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