NRES: the network of robotic echelle spectrographs

Abstract

Las Cumbres Observatory Global Telescope Network (LCOGT) has built the Network of Robotic Echelle Spectrographs (NRES), consisting of four identical, high-resolution optical spectrographs, each fiber-fed simultaneously by up to two 1-meter telescopes and a calibration source. Two units have been installed and are currently executing scientific observations. A third unit has been installed and is presently in commissioning. A fourth unit has been shipped to site and will be installed in mid 2018. Operating on four separate continents in both the Northern and Southern hemispheres, these instruments comprise a globally-distributed, autonomous spectrograph facility for stellar classification and high-precision radial velocity of bright stars. Simulations suggest we will achieve long-term radial velocity precision of 3 m/s in less than an hour for stars with V < 12. Radial velocity precision of 75 m/s has already been demonstrated with our automatic data-processing pipeline across multiple sites. Work is ongoing to improve several NRES system components including telescope control (robotic source acquisition in particular) and the data-processing pipeline. In this document we briefly overview the NRES design, its purpose and goals, results achieved to date in the field, and the ongoing development effort to improve instrument performance.