A Two-Colour CCD Survey of the North Celestial Cap: I. The Method

TL;DR

This paper details a new CCD survey of the North Celestial Cap, focusing on its methodology, including observations, data processing, and catalog creation, to improve coverage in a poorly studied sky region.

Contribution

It introduces a novel survey method using the LAIWO mosaic CCD camera for the NCC region, providing detailed procedures and data quality assessments.

Findings

Achieved ~1 arcsec astrometry accuracy

Photometry accurate to ~0.1 mag for bright sources

Survey complete to limiting magnitudes of R=20.6 and I=19.6

Abstract

We describe technical aspects of an astrometric and photometric survey of the North Celestial Cap (NCC), from the Pole (DEC=90 deg) to DEC=80 deg, in support of the TAUVEX mission. This region, at galactic latitudes from ~ 17 deg to ~ 37 deg, 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 subarcsec 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.