The COSMOS Survey: Hubble Space Telescope / Advanced Camera for Surveys (HST/ACS) Observations and Data Processing

We describe the details of the Hubble Space Telescope (HST) Advanced Camera for Surveys / Wide Field Channel (ACS/WFC) observations of the COSMOS field, including the data calibration and processing procedures. We obtained a total of 583 orbits of HST ACS/WFC imaging in the F814W filter, covering a field that is 1.64 degrees2 in area, the largest contiguous field ever imaged with HST. The median exposure depth across the field is 2028 seconds (one HST orbit), achieving a limiting point-source depth AB(F814W) = 27.2 (5 sigma). We also present details about the astrometric image registration, distortion removal and image combination using MultiDrizzle, as well as motivating the choice of our final pixel scale (30 milliarcseconds per pixel), based on the requirements for weak lensing science. The final set of images are publicly available through the archive sites at IPAC and STScI, along with further documentation on how they were produced. Subject headings: cosmology: observations — cosmology: large scale structure of universe — cosmology: dark matter — galaxies: formation — galaxies: evolution — surveys Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA Inc, under NASA contract NAS 5-26555. Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 Institute for Astronomy, 2680 Woodlawn Dr., University of Hawaii, Honolulu, Hawaii, 96822 Service d’Astrophysique, CEA/Saclay, 91191 Gif-sur-Yvette, France California Institute of Technology, MC 105-24, 1200 East California Boulevard, Pasadena, CA 91125 Laboratoire d’Astrophysique de Marseille, BP 8, Traverse du Siphon, 13376 Marseille Cedex 12, France Institut d’Astrophysique de Paris, UMR7095 CNRS, Universitè Pierre et Marie Curie, 98 bis Boulevard Arago, 75014 Paris, France Observatoire de Paris, LERMA, 61 Avenue de l’Observatoire, 75014 Paris, France Jet Propulsion Laboratory, Pasadena, CA 91109 Visiting Astronomer, Univ. Hawaii, 2680 Woodlawn Dr., Honolulu, HI, 96822