THE ESO SLICE PROJECT (ESP) GALAXY REDSHIFT SURVEY. I. DESCRIPTION AND FIRST RESULTS

TheESOSliceProject(ESP)isagalaxyredshiftsur- vey we have recently completed as an ESO Key-Project. The ESP covers 23.3 square degrees in a region close to the South Galactic Pole. The survey is nearly complete (85%) to the lim- iting magnitude bJ =1 9 :4 and consists of 3342 galaxies with reliable redshift determination. In this paper, the rst in a series that will present the results of the ESP survey, we describe the main characteristics of the survey and briefly discuss the properties of the galaxy sample. From a preliminary spectral analysis of a large sub-sample of 2550 galaxies we nd that the fraction of actively star-forming galaxies increases from a few percent for the brightest galax- ies up to about 40% for the galaxies fainter than M = 16:5 +5logh . The most outstanding feature in the ESP redshift distribu- tion is a very signicant peak at z ' 0:1. The detection of similar peaks, at the same distance, in other surveys in the same regionofthesky,suggeststhepresenceofalargebidimensional structure perpendicular to the line of sight. The minimum size of this structure would be of the order of 100 50 h 1 Mpc , comparable with the size of the Great Wall.