S-cosmos: the Spitzer Legacy Survey of the Hst-acs 2 ⊓ ⊔ @bullet Cosmos Field * I: Survey Strategy and First Analysis

The Spitzer-COSMOS survey (S-COSMOS) is a Legacy program (Cycles 2+3) designed to carry out a uniform deep survey of the full 2⊓⊔ COSMOS field in all seven Spitzer bands (3.6, 4.5, 5.6, 8.0, 24.0, 70.0, 160.0μm). This paper describes the survey parameters, mapping strategy, data reduction procedures, achieved sensitivities to date, and the complete data set for future reference. We show that the observed infrared backgrounds in the S-COSMOS field are within 10% of the predicted background levels. The fluctuations in the background at 24μm have been measured and do not show any significant contribution from cirrus, as expected. In addition, we report on the number of asteroid detections in the low galactic latitude COSMOS field. We use the Cycle 2 S-COSMOS data to determine preliminary number counts, and compare our results with those from previous Spitzer Legacy surveys (e.g. SWIRE, GOODS). The results from this “first analysis” confirm that the SCOSMOS survey will have sufficient sensitivity with IRAC to detect ∼ L disks and spheroids out to z & 3, and with MIPS to detect ultraluminous starbursts and AGN out to z ∼ 3 at 24μm and out to z ∼ 1.5 − 2 at 70μm and 160μm. Subject headings: infrared: galaxies — cosmology: observations — cosmology: large scale strutcure of universe — 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; also based on data collected at : the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan; the XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA; the European Southern Observatory under Large Program 175.A0839, Chile; Kitt Peak National Observatory, Cerro Tololo InterAmerican Observatory, and the National Optical Astronomy Observatory, which are operated by the Association of Universities for Research in Astronomy, Inc. (AURA) under cooperative agreement with the National Science Foundation; the National Radio Astronomy Observatory which is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc ; and and the Canada-France-Hawaii Telescope with MegaPrime/MegaCam operated as a joint project by the CFHT Corporation, CEA/DAPNIA, the National Research Council of Canada, the Canadian Astronomy Data Centre, the Centre National de la Recherche Scientifique de France, TERAPIX and the University of Hawaii. 1 Institute for Astronomy, 2680 Woodlawn Dr., University of Hawaii, Honolulu, Hawaii, 96822; sanders@ifa.hawaii.edu 2 California Institute of Technology, MS 105-24, 1200 East California Boulevard, Pasadena, CA 91125 3 CNRS, AIM – Unité Mixte de Recherche CEA – CNRS – Université Paris VII – UMR n 7158, 91191 Gif-sur-Yvette, France 4 Visiting Astronomer, Univ. Hawaii, 2680 Woodlawn Dr., Honolulu, HI, 96822 5 Spitzer Science Center, MS 314-6, California Institute of Technology, Pasadena, CA 91125 6 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 7 National Radio Astronomy Observatory, P.O. Box 0, Socorro, NM 87801-0387 8 Department of Physics, ETH Zurich, CH-8093 Zurich, Switzerland 9 INAF-Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy