The Keck-FOBOS spectroscopic facility: Conceptual design

Kevin Bundy, Kyle B. Westfall, Nick MacDonald, Renate Kupke, Claire Poppett, Timothy N. Miller, Jon Lawrence, Celestina Saavedra Lacombea, Renbin Yan, Michael Goodwin, Marc Kassis, John O'Meara, Daniel Masters, Joseph Burchett, Benjamin Williams, Michael Rich, V. Ashley Villar, Nathan Sandford, Yuan Sen Ting, Phil HinzChad Schafer, Rachel Mandelbaum, Marina Huang, J. Xavier Prochaska, Puragra Guhathakurta

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

1 Scopus citations


The Fiber Optic Broad-band Optical Spectrometer (FOBOS) is a high-priority spectroscopic facility concept for the W. M. Keck Observatory. Here, we provide an update on the FOBOS conceptual design. FOBOS will deploy 1800 fibers across the 20-arcminute field-of-view of the Keck II Telescope. Starbugs fiber positioners will be used to deploy individual fibers as well as fiber-bundle arrays (integral field units, IFUs). Different combinations of active single fibers or IFUs can be selected to carry light to one of three mounted spectrographs, each with a 600-fiber pseudoslit. Each spectrograph has four wavelength channels, enabling end-to-end instrument sensitivity greater than 30% from 0.31-1.0 µm at a spectral resolution of R ∼ 3500. With its high fiber density on a large telescope and modest field-of-view, FOBOS is optimized to obtain deep spectroscopy for large samples. In single-fiber mode, it will deliver premier spectroscopic reference sets for maximizing the information (e.g., photometric redshifts) that can be extracted from panoramic imaging surveys obtained from the forthcoming Rubin and Roman Observatories. Its IFUs will map emission from the circumgalactic interface between forming galaxies and the intergalactic medium at z ∼ 2-3, and lay the path for multiplexed resolved spectroscopy of high-z galaxies aided by ground-layer and multi-object adaptive optics. In the nearby universe, its high sampling density and combination of single-fiber and IFU modes will revolutionize our understanding of the M31 disk and bulge via stellar populations and kinematics. Finally, with a robust and intelligent target and program allocation system, FOBOS will be a premier facility for follow-up of rare, faint, and transient sources that can be interleaved into its suite of observing programs. With a commitment to delivering science-ready data products, FOBOS will enable unique and powerful combinations of focused, PI-led programs and community-driven observing campaigns that promise major advances in cosmology, galaxy formation, time-domain astronomy, and stellar evolution.

Original languageEnglish
Title of host publicationGround-Based and Airborne Instrumentation for Astronomy VIII
EditorsChristopher J. Evans, Julia J. Bryant, Kentaro Motohara
ISBN (Electronic)9781510636811
StatePublished - 2020
EventGround-Based and Airborne Instrumentation for Astronomy VIII 2020 - Virtual, Online, United States
Duration: Dec 14 2020Dec 22 2020

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


ConferenceGround-Based and Airborne Instrumentation for Astronomy VIII 2020
Country/TerritoryUnited States
CityVirtual, Online

Bibliographical note

Funding Information:
∗For the first ten years of operation, Vera C. Rubin Observatory will perform the Rubin Observatory Legacy Survey of Space and Time (LSST). The National Science Foundation (NSF) and the US Department of Energy (DOE) are joint partners in the Rubin Observatory Project and Operations. †Euclid is led by the European Space Agency with significant NASA involvement and will launch in 2022. Its primary mission is a 15,000 deg2 imaging and grism survey in optical and near-IR wavebands. ‡Previously known as the Wide Field Infrared Survey Telescope (WFIRST), the Roman Space Telescope is expected to launch in the mid 2020’s. §The W. M. Keck Observatory (WMKO) operates the twin 10m Keck Telescopes.

Publisher Copyright:
© 2020 SPIE


  • Ground-based astronomical instruments

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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