The Advanced Camera for Surveys

摘要

The Advanced Campera fr Surveys (ACS) is a third generation instrument for the Hubble Space Telescope (HST). It is currently planned for installation in HST during the fourth servicing mission in SUmmer 2001. The ACS will has three cameras. The first, the Wide Field Camera (WFC) is a high-throughput (approx42percent at 600 nm, including the HST OTA), wide field imaging camera optimized for the near-IR. WFC has a 202" x 202" field of view with a plate scale of 0.05"/pixel, delivered by a mosatic of two 2048 x 4096 CCDs. The WFC is designed to achieve a factor of 10 increase in discovery efficiency at 800 nm, where discovery efficiency is defined as the product of field of view and instrument throughput. The second, the High Resolution Camera (HRC) is a near-UV optimized camera designed for critically sampled imaging in hte visible, with the capability for high contrast, coronographic imaging. The HRC has a field of view of 26" x 29" with a plate scale of 0.027"/pixel. The third camera is the Solar Blind Camera (SBC), which is optimized for far-UV imaging. The SBC has a field of view of 31" x 35" with a plate scale of 0.032"/pixel. The ACS science team will employ approx60percent of the dedicated GTO time to conducting a WFC deep survey of clusters of galaxies at intermediate redshift, mapping the large scale distribution of dark matter around low redshift clusters, and studying the nature of galaxies at z>4. HRC observatiosn of a sample of early galaxies will be surveyed for nuclear disks, and comibned with spectroscopic observations to measure central masses and determine if black holes are present. A novel polarimetric technique will be used to measure geometric distances to galaxies and oprovide an independent measure of H_0. The HRC coronograph will be used to conduct studies of dust disks around nearby stars and to search for planets.