The Hubble Deep Field south: Formulation of the observing campaign

Deep, multiband observations of high Galactic latitude fields are an essent ial tool for studying topics ranging from Galactic structure to extragalact ic background radiation. The Hubble Deep Field (HDF-N) observations obtaine d in 1995 December established a standard for such narrow, deep surveys. Th e held has been extensively analyzed by a variety of groups and has been wi dely studied with imaging and spectroscopy over wavelengths ranging from 10 (-3) to 2 x 10(5) mum. We describe here a second deep field campaign (HDF-S ), this time in the southern hemisphere, undertaken by the Hubble Space Tel escope (HST) in 1998 October in a program very similar to the northern Hubb le Deep Field. Imaging and spectroscopy of three adjacent fields in the sou thern continuous viewing zone were obtained simultaneously for 150 orbits, and a mosaic of flanking fields was imaged for 27 additional orbits. Two im portant features of the HDF-S distinguish it from the HDF-N: the campaign i ncluded parallel observations by the three main HST instruments-WFPC2, STIS , and NICMOS-and the HDF-S location was selected to place a bright z = 2.24 quasar in the STIS field of view. The HDF-S observations consist of WVFPC2 images in filters close to U, B, y, and I, a deep STIS image of the held s urrounding the quasar, spectroscopy of the quasar with STIS from 1150 to 35 60 Angstrom and deep imaging of an adjacent field with NICMOS camera 3 at 1 .1, 1.6, and 2.2 mum. All of the HDF-S data were fully reduced and made pub licly available within 2 months of the observations, and we describe here t he selection of the fields and the observing strategy that was employed. De tailed descriptions of the data and the reduction techniques for each field , together with the corresponding source catalogs, appear in separate paper s.