LRS2: the new facility low resolution integral field spectrograph for the Hobby-Eberly Telescope
Abstract
The second generation Low Resolution Spectrograph (LRS2) is a new facility instrument for the Hobby-Eberly Telescope (HET). Based on the design of the Visible Integral-field Replicable Unit Spectrograph (VIRUS), which is the new flagship instrument for carrying out the HET Dark Energy Experiment (HETDEX), LRS2 provides integral field spectroscopy for a seeing-limited field of 12 x 6 arcseconds. For LRS2, the replicable design of VIRUS has been leveraged to gain broad wavelength coverage from 370 nm to 1 micron, spread between two fiber-fed dual-channel spectrographs, each of which can operate as an independent instrument. The blue spectrograph, LRS2-B, covers 370-470 nm and 460-700 nm at fixed resolving powers of ~1900 and ~1100, respectively, while the red spectrograph, LRS2-R, covers 650-842 nm and 818-1050 nm with both of its channels having a resolving power of ~1800. In this paper, we present a detailed description of the instrument's design in which we focus on the departures from the basic VIRUS framework. The primary modifications include the fore-optics that are used to feed the fiber integral field units at unity fill-factor, the cameras' correcting optics and detectors, and the volume phase holographic grisms. We also present a model of the instrument's sensitivity and a description of specific science cases that have driven the design of LRS2, including systematically studying the spatially resolved properties of extended Lyman-alpha blobs at 2 < z < 3. LRS2 will provide a powerful spectroscopic follow-up platform for large surveys such as HETDEX.
Keywords
Cite
@article{arxiv.1407.6016,
title = {LRS2: the new facility low resolution integral field spectrograph for the Hobby-Eberly Telescope},
author = {Taylor S. Chonis and Gary J. Hill and Hanshin Lee and Sarah E. Tuttle and Brian L. Vattiat},
journal= {arXiv preprint arXiv:1407.6016},
year = {2015}
}
Comments
26 pages, 14 figures, 3 tables. To be published in Proc. SPIE, 2014, "Ground-Based and Airborne Instrumentation for Astronomy V", 9147-9. arXiv admin note: text overlap with arXiv:1207.6118