The COSMOS Survey: <i>Hubble Space Telescope</i> Advanced Camera for Surveys Observations and Data Processing

TLDR

The paper details the HST ACS/WFC observations of the COSMOS field, including calibration, processing, and the rationale for the chosen 30 mas pixel scale for weak‑lensing studies. The survey used 583 HST orbits to image 1.64 deg² in F814W, with images processed via MultiDrizzle for astrometric registration, distortion correction, and combination. The data reach a median depth of 2028 s (AB = 27.2) and are publicly released through IPAC and STScI archives.

Abstract

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 square degrees 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.