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

• Published in: Astrophysics and space science 2010-04, Vol.326 (2), p.203-217
• Main Authors: Gorbikov, Evgeny, Brosch, Noah, Afonso, Cristina
• Format: Article
• Language: English
• Subjects: Astrobiology; Astronomy; Astrophysics; Astrophysics and Astroparticles; Cosmology; Observations and Techniques; Original Article; Physics; Physics and Astronomy; Polls & surveys; Space Exploration and Astronautics; Space Sciences (including Extraterrestrial Physics; Stars & galaxies
• ISSN: 0004-640X; 1572-946X
• DOI: 10.1007/s10509-009-0242-0

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.