The Dark Energy Spectrometer: a potential multi-fiber instrument for the Blanco 4-meter Telescope

Abstract

We describe the preliminary design of the Dark Energy Spectrometer (DESpec), a fiber-fed spectroscopic instrument concept for the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory (CTIO). DESpec would take advantage of the infrastructure recently deployed for the Dark Energy Camera (DECam). DESpec would be mounted in the new DECam prime focus cage, would be interchangeable with DECam, would share the DECam optical corrector, and would feature a focal plane with ~4000 robotically positioned optical fibers feeding multiple high-throughput spectrometers. The instrument would have a field of view of 3.8 square degrees, a wavelength range of approximately 500<<1000 nm, and a spectral resolution of R~3000. DESpec would provide a powerful spectroscopic follow-up system for sources in the Southern hemisphere discovered by the Dark Energy Survey and LSST.λ