The ATESP radio survey I. Survey description, observations and data reduction

This paper is the first of a series reporting the results of the Australia Telescope ESO Slice Project (ATESP) radio survey obtained at 1400 MHz with the Australia Telescope Compact Array (ATCA) close to the South Galactic Pole (SGP) over the region covered by the ESO Slice Project (ESP) galaxy redshift survey (delta similar to -40 degrees). The survey consists of 16 radio mosaics with similar to 8 " X 14 " resolution and uniform sensitivity (1 sigma noise level similar to 79 mu Jy) over an area of similar to 26 sq. degrees. Here we present the design of the survey, we describe the mosaic observing technique which was used to obtain an optimal combination of uniform and high sensitivity over the whole area, and the data reduction: the problems encountered and the solutions adopted.