=========================================================================== COSMOS HST/ACS Data (g-band) Version 1.2 =========================================================================== The Cosmic Evolution Survey (COSMOS) is an HST Treasury Project to survey a 2 square degree equatorial field, centered on RA=10:00:28.6 and DEC=+02:12:21.0, using the ACS camera. The project also incorporates major commitments from other observatories around the world, including the VLA radio telescope, ESO's VLT in Chile, ESA's XMM X-ray satellite, and the Japanese 8-meter Subaru telescope in Hawaii. These data represent the second public release of the COSMOS observations from the ACS instrument on HST. Included in this release are 8 pointings from the center of the survey area, observed using the F475W (g-band) filter. The key characteristics of these data: Instrument: HST Advanced Camera for Surveys (ACS) Dates of observations: Cycle 13 (Jul 2004 - Jun 2005) Observing time: 4 exposures / 1 orbit / pointing Filter: F475W (g-band) Area: ~1 sq deg Resolution: 0.05"/pixel (drizzled data) These data were reduced by Anton Koekemoer (koekemoer@stsci.edu) using the MultiDrizzle software package (Koekemoer et all. 2002). More information on MultiDrizzle can be found here: Koekemoer, A. M., Fruchter, A. S., Hook, R. H., Hack, W. 2002, HST Calibration Workshop, p. 337 http://www.stsci.edu/hst/acs/analysis/multidrizzle The data products available here include: (1) drizzled, flux calibrated, astrometrically correct images, rotated such that north is up, east to the left (2) corresponding weight images (exposure maps) The image files follow a standard naming scheme where, for example: acs_g_100013+0209_sci_12.fits refers to an HST/ACS g-band (F475W) mosaic image centered at RA=10:00:13 and DEC=+02:09, version 1.2. Both science images ("_sci_" in file name) and weighting images ("_wht_" in file name) are provided. Please note: The COSMOS ACS FITS images contain floating point data but do not use IEEE NaN values to denote blank pixels. Rather each image has an associated weight image mask (also a floating point FITS image) that should be used to weight image operations. In particular, mask values of zero indicate areas of no data (including pixels masked off because of radiation hits). Further information may be obtained from the main COSMOS web page: http://cosmos.astro.caltech.edu/ and the COSMOS HST/ACS web page: http://www.stsci.edu/~koekemoe/cosmos/ =========================================================================== The COSMOS Team, Patrick Shopbell (Archive Lead), and Anton Koekemoer pls@astro.caltech.edu, koekemoer@stsci.edu November 13, 2005