The 2dF Galaxy Redshift Survey: spectra and redshifts


  • 1 The Digitized Sky Survey was produced at the Space Telescope Science Institute, and is based on photographic data obtained using the Oschin Schmidt Telescope on Palomar Mountain and the UK Schmidt Telescope.


The 2dF Galaxy Redshift Survey (2dFGRS) is designed to measure redshifts for approximately 250 000 galaxies. This paper describes the survey design, the spectroscopic observations, the redshift measurements and the survey data base. The 2dFGRS uses the 2dF multifibre spectrograph on the Anglo-Australian Telescope, which is capable of observing 400 objects simultaneously over a 2° diameter field. The source catalogue for the survey is a revised and extended version of the APM galaxy catalogue, and the targets are galaxies with extinction-corrected magnitudes brighter than inline image. The main survey regions are two declination strips, one in the southern Galactic hemisphere spanning inline image around the SGP, and the other in the northern Galactic hemisphere spanning inline image along the celestial equator; in addition, there are 99 fields spread over the southern Galactic cap. The survey covers 2000 deg2 and has a median depth of inline image. Adaptive tiling is used to give a highly uniform sampling rate of 93 per cent over the whole survey region. Redshifts are measured from spectra covering inline image at a two-pixel resolution of 9.0 Å and a median S/N of 13 pixel−1. All redshift identifications are visually checked and assigned a quality parameter Q in the range inline imageinline image redshifts are 98.4 per cent reliable and have an rms uncertainty of 85 km s−1. The overall redshift completeness for inline image redshifts is 91.8 per cent, but this varies with magnitude from 99 per cent for the brightest galaxies to 90 per cent for objects at the survey limit. The 2dFGRS data base is available on the World Wide Web at