2. The data
The ESO Slice Project (ESP) galaxy redshift survey is described in Vettolani et al. (1997). The data of the full sample together with a detailed description of the instrumental set-up and of the data reduction can be found in Vettolani et al. (1998). Here we only briefly describe the survey.
The ESP survey extends over a strip of (strip A), plus a nearby area of (strip B), five degrees West of the main strip, in the South Galactic Pole region ( and respectively; ). Each of the two strips is covered with two rows of slightly overlapping circular fields of angular radius arcmin, the separation between the centers of neighboring circles being 30 arcmin. Each field corresponds to the field of view of the multifiber spectrograph OPTOPUS at the 3.6m ESO telescope that was used to obtain almost all of the spectra (the MEFOS spectrograph was used in the last ESP run). Throughout this paper we will assume that the circular fields are tangent, with an angular radius of 15 arcmin: this simplification has no consequences on the galaxy sample. The total solid angle of the spectroscopic survey is 23.2 square degrees.
The spectra cover the wavelength range 3730Å to 6050Å, with an average pixel size of 4.5Å. Galaxy redshifts are measured by cross-correlating sky-subtracted spectra with a set of 8 template stars observed with the same instrumental set-up used to obtain the galaxy spectra. In this paper we use emission line redshifts only for galaxies with no reliable absorption line redshift. The median internal velocity error is of the order of km s-1 . From a comparison of our 8 templates with three SAO radial velocity standard stars we estimate that the zero-point error should be smaller than km s-1 .
The total number of confirmed galaxies with reliable redshift measurement is 3342. The completeness of strip A and strip B are estimated to be 91% and 67% respectively.
© European Southern Observatory (ESO) 1999
Online publication: December 22, 1998