While astronomical images can offer breathtaking records of the appearance of the Universe, far greater information is obtained by dividing a light beam according to color (a technique known as spectroscopy). This approach can yield important details about the physical properties of the source: its temperature, chemical composition, density, mass, and velocity, among others. Constructing very efficient, wide spectral coverage, high-resolution mapping spectrographs is therefore an effective approach to getting the most from our very largest ground-based telescopes. Dr. H. Lewis (California Association for Research in Astronomy together with the California Institute of Technology and the University of California) proposes to complete the development of the Keck Cosmic Web Imager spectrograph for the 10-m Keck II telescope atop Mauna Kea, Hawaii with new optics optimized for the red portion of the spectrum. The final instrument will provide an extraordinary platform for carrying out sensitive assessments of galaxy formation and evolution in the first few hundred million years after the Big Bang, to study the interstellar medium in external galaxies, to probe star clusters and nebulae in our own Milky Way galaxy, and to track the process of star formation within those clusters.
The Keck Cosmic Web Imager (KCWI) is designed to provide seeing-limited visible band, integral field spectroscopy with moderate to high spectral resolution (up to R = 20,000), selectable slicer scales and fields of view, high efficiency, and excellent sky subtraction. KCWI will benefit from the Keck II telescope's large, 10-m aperture and excellent site, providing a dual-channel, modular implementation. The blue channel of KCWI is nearly complete; the red channel to be funded through this proposal will extend the spectral coverage to the entire optical window from 3500 to 10500 angstroms and enable scientists to address several of the key questions relating to the process of the formation and evolution of external galaxies, and thereby of the development of matter in the universe.
Funding for the development of the red channel of the Keck Cosmic Web Imager is being provided by NSF's Division of Astronomical Sciences through its participation in the Major Research Instrumentation program.
